JP2012191537A - Impulse wireless transmission device, and transmission method of impulse wireless transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impulse wireless transmission device performing data wireless transmission using an impulse.SOLUTION: An impulse wireless transmission device is configured to have: a short pulse generator outputting a short pulse based on logic "1" in a data signal; a bandpass filter receiving the short pulse to extract an RF pulse signal in a frequency band to be used in communication; a transmission amplifier amplifying the extracted RF pulse signal; and an antenna for outputting the amplified RF pulse signal. The short pulse generator outputs the short pulse overrated to have a higher frequency than the maximum transmission rate for passing thorough the bandpass filter in the case that a transmission rate of the data signal is lower than the maximum transmission rate.

Description

  The present invention relates to an impulse radio transmission apparatus that performs radio transmission of data using impulses.

  Impulse radio is a radio transmission that uses RF pulse signals as a transmission medium, and can reduce the number of oscillators, mixers, etc., which were indispensable in the past. There is. Such impulse radio is expected to be applied to a broadband radio communication system exceeding 10 Gbps.

  The general configuration of the impulse radio transmission apparatus 10 is shown in FIG. 8, where the RF transmission unit 20 includes a short pulse generator 21, a bandpass filter 22, a transmission amplifier 23, and an antenna 24, and the RF reception unit 30 includes an antenna. 31, a receiving amplifier 32, a band pass filter 33 and a detector 34.

  In the RF transmitter 20, a data signal (for example, 10 Gbps) that is the input signal 20 a is converted into a short pulse 20 b by a short pulse generator 21 and input to a bandpass filter 22. The short pulse 20b has a wide frequency component, and only the frequency component used for communication is extracted by the band pass filter 22, and is output as the RF pulse signal 20c. The pulse width of the RF pulse signal 20 c at this time is a value of the reciprocal of the maximum transmission rate possible with the pass frequency bandwidth of the band pass filter 22. The transmission amplifier 23 amplifies the RF pulse signal 20c output from the bandpass filter 22 to a specified power, and radiates the amplified RF pulse signal 20d to the space via the antenna. In the signal radiated from the antenna, the portion where the RF pulse signal 20 d exists corresponds to “1” of the data signal, and the portion where the RF pulse signal 20 d does not corresponds to “0” of the data signal. In the receiving unit 30, the RF pulse signal 30a input via the antenna is amplified by the receiving amplifier 32, then filtered by the band pass filter 33, envelope detection is performed by the detector 34, and the data signal 30b is decoded. .

  The short pulse 20b generated by the short pulse generator 21 has a wide frequency component (spectrum from direct current to high frequency) as described above, and has energy as shown in FIG. By passing the short pulse 20b through the band-pass filter 22, a frequency spectrum having the energy of the pass band Bbpf of the band-pass filter 22 indicated by the oblique line in FIG. 9 is extracted.

  In the impulse radio transmission apparatus 10 having this configuration, when the pass frequency bandwidth Bbpf of the bandpass filter 22 is equal to the assigned frequency bandwidth, the transmission rate Br of the data signal is the maximum transmission that can pass the pass frequency bandwidth Bbpf. The speed can be increased to Bmax. However, in general, it is rare that the maximum transmission rate Bmax can always be exhibited depending on the state of the transmission channel due to the weather or the like, and it is often operated at a transmission rate lower than the maximum transmission rate Bmax.

  When transmitting at a low transmission rate, the problem is that the SNR (signal-to-noise ratio) deteriorates. For example, a case where a maximum transmission rate of 10 Gbps is operated at 2.5 Gbps is considered with reference to FIG. FIG. 10A shows the waveform of the RF pulse signal with respect to the waveform of the data signal when the transmission speed Br of the data signal is transmitted at 10 Gbps. On the other hand, FIG. 10B shows the waveform of the RF pulse signal with respect to the waveform of the data signal when transmitted at Br = 2.5 Gbps. As can be seen from both figures, the waveform of the RF pulse signal is the same, but the pulse appearance frequency at one symbol time ts when transmitting at 2.5 Gbps is ¼ compared to 10 Gbps.

  On the other hand, the noise power Pn of the RF receiver 30 is proportional to the frequency bandwidth Bbpf as shown by the following equation (k is Boltzmann constant, T is absolute temperature).

Pn = kTBbpf (W)
This means that if reception is performed using bandpass filters having the same frequency bandwidth Bbpf regardless of the transmission speed of data to be transmitted, reception is performed with the same noise power. Therefore, when a 2.5 GHz signal is received, the power of the data signal is ¼ as described above, so the SNR is lowered to ¼.

  In order to suppress a decrease in SNR, it is known that the passband Bbpf of the bandpass filter is made equal to the assigned frequency bandwidth and the RF pulse signal is repeatedly output within one symbol time. For example, as shown in FIG. 11, when a passband Bbpf of a bandpass filter is 10 GHz (that is, the maximum transmission rate Bmax can be 10 GHz) and a data signal is transmitted at a transmission rate of 2.5 Gbps, 10 Gbps In this case, four RF pulse signals having the same pulse width as those in the above case are repeatedly output within one symbol time ts (400 ps). FIG. 11A shows a data signal and an RF pulse signal at a transmission rate of 10 Gbps as in FIG. 10A, and FIG. 11B outputs four RF pulse signals in a transmission of 2.5 Gbps. A state is shown (three RF pulse signals surrounded by dotted lines are added to show four RF pulse signals). By doing so, the signal power is quadrupled, and the SNR is improved as compared with that shown in FIG.

JP 2006-74432 A

  As described above, in the impulse radio transmission apparatus, data transmission is performed at a speed slower than the maximum transmission speed depending on the communication channel state. In this case, however, there is a problem that the SNR is lowered. If the impulse radio transmission device is provided with a band-pass filter having a pass band corresponding to the data transmission rate, the problem of a decrease in SNR is solved. However, a structure for switching the bandpass filter in accordance with the data transmission speed is required, which is disadvantageous in terms of size and cost. In addition, the band-pass filter is also a millimeter-wave signal passing path, and there is a problem that providing a switching mechanism in the part may cause deterioration of the characteristics of the RF pulse signal.

  Further, although the above-described method of repeatedly inserting an RF pulse signal within one symbol time improves the SNR as compared with the case where it is not inserted, since the repeated RF pulse signal is independent, the clock signal is derived from the received signal. Cannot be extracted, and some ingenuity is required in data reproduction. Moreover, it cannot be said that the improvement amount of SNR is sufficient, and further improvement is necessary.

  The present invention provides an impulse radio transmission apparatus capable of improving the SNR by transmitting an RF pulse signal with increased signal power on the transmission side and easily reproducing data on the reception side in data transmission at a low transmission rate. The purpose is to do.

  According to one aspect of the present invention, an impulse radio transmission apparatus according to the present invention includes a short pulse generator that outputs a short pulse based on logic “1” of a data signal, and a frequency band that is used for communication after receiving the short pulse. The short pulse generator has a band-pass filter that extracts an RF pulse signal, a transmission amplifier that amplifies the extracted RF pulse signal, and an antenna that outputs the amplified RF pulse signal. Provided is an impulse radio transmission apparatus that outputs an overrated short pulse whose frequency is faster than the maximum transmission speed when the transmission speed is lower than the maximum transmission speed that can pass through the bandpass filter.

  According to another aspect of the invention, a transmission method of an impulse radio transmission apparatus according to the present invention includes a short pulse generator that outputs a short pulse based on a logic “1” of a data signal, and a communication that receives the short pulse and performs communication. A transmission method of an impulse radio transmission apparatus comprising: a bandpass filter that extracts an RF pulse signal in a frequency band to be used; a transmission amplifier that amplifies the extracted RF pulse signal; and an antenna that outputs the amplified RF pulse signal. Thus, there is provided a transmission method for an impulse radio transmission apparatus that outputs an overrated short pulse whose frequency is faster than the maximum transmission rate when the short pulse generator is slower than the maximum transmission rate capable of passing through the frequency band.

  At low transmission speed, continuous RF pulse signal occupies within one symbol time of data signal on the transmission side, so that the amount of power of RF pulse signal can be increased and impulse radio transmission with greatly improved SNR on the reception side Equipment can be provided.

It is a figure which shows the structural example of the impulse radio | wireless transmission apparatus of this invention. It is a figure explaining SNR improvement when a transmission rate is low. It is a figure which shows the circuit example and time chart example of an over-rate short pulse generator. It is a figure which shows the example of a waveform of RF pulse signal of this invention. It is a figure which shows the n multiplication overrate short pulse generation circuit and a time chart example. It is a figure which shows the example of RF pulse signal preparation by the 2 times and 3 times over rate short pulse. It is a figure which shows the example of creation of a band pass filter. It is a figure which shows the general structural example of an impulse radio | wireless transmission apparatus. It is a figure which shows the spectrum example of a short pulse. It is a figure which shows the figure explaining the SNR fall when a transmission rate is low. It is a figure which shows the example of SNR reduction by a repetitive RF pulse signal.

  The structure of the impulse radio transmission apparatus 100 of the present invention is shown in FIG. FIG. 1 is drawn corresponding to FIG. 8 described above, and the same components and signal waveforms are denoted by the same reference numerals. The impulse radio transmission apparatus 100 includes an RF transmitter 200 and an RF receiver 30, and the configuration of the RF receiver 30 is the same as that shown in FIG. The configuration of the RF transmission unit 200 includes an overrate short pulse generator 210, a bandpass filter 22, a transmission amplifier 23, and an antenna 24. The short pulse generator 21 in FIG. 8 is replaced with the overrate short pulse generator 210. It is a configuration.

  The overrate short pulse generator 210 generates a short pulse train with an appearance frequency corresponding to twice the maximum transmission rate Bmax that can pass through the bandpass filter 22 based on the data signal 200a and the clock signal 201a. Here, the generated short pulse train is referred to as an overrate short pulse 200b. The bandpass filter 22 extracts the frequency spectrum of the frequency band Bbpf of the bandpass filter 22 included in the generated overrate short pulse 200b, and outputs an RF pulse signal 200c having a large pulse width. The transmission amplifier 23 amplifies the RF pulse signal 200 c output from the band pass filter 22 to a specified power, and radiates the amplified RF pulse signal 200 d to the space via the antenna 24.

  The receiving unit 30 processes the RF pulse signal 300a having a large pulse width with the same configuration as that shown in FIG. That is, the weak RF pulse signal 300a input through the antenna is amplified by the receiving amplifier 32, then filtered by the band pass filter 33, envelope detection is performed by the detector 34, and the data signal 300b is decoded. Since the RF pulse signal 300a has a higher signal power than the RF pulse signal 30a shown in FIG. 8, the SNR is improved.

  The overrate short pulse 200b generated by the overrate short pulse generator 210 and the RF pulse signal 200c having a large pulse width generated thereby will be described in detail with reference to FIGS.

  FIG. 2A is a diagram in which portions of the overrate short pulse generator 210 and the bandpass filter 22 in the RF transmission unit 200 shown in FIG. 1 are cut out. Here, the transmission rate Br of the data signal 200a is 2.5 Gbps, and the frequency band Bbpf of the bandpass filter 22 is 10 GHz. In the overrate short pulse generator 210, it is assumed that the overrate short pulse is generated with the appearance frequency twice the maximum transmission speed Bmax that can pass through the band pass filter 22 by the clock signal 201a. Since the frequency band Bbpf of the band pass filter 22 is 10 GHz, the maximum transmission speed Bmax is 10 GHz, and the overrate short pulse 200b is generated at 20 GHz which is twice this frequency.

  FIG. 2B shows an overrate short pulse 200b generated by the overrate short pulse generator 210 with respect to the data signal shown in FIG. 2A and a band-pass filter 22 from the input overrate short pulse 200b. Each waveform of the output RF pulse signal 200c is shown.

  The data signal 200a shown in FIG. 2B indicates "1011" data, and one symbol time is 400 ps (1 / 2.5 Gbps). Since the overrate short pulse 200b generates a short pulse at 20 GHz, eight short pulses (the time interval of the short pulses is 50 ps) are generated within one symbol time. Since the band pass filter 22 converts an RF pulse signal having a pulse width of 100 ps (1/10 GHz) from one short pulse, eight RF pulse signals 200c (the time interval of the RF pulse signal is set to 400 ps of one symbol time). 50 ps) is converted. Therefore, these eight RF pulse signals are overlapped and continuous within one symbol time, and as a result, converted into an RF pulse signal 200c having a pulse width equal to one symbol time. The RF pulse signal 200c in FIG. 2B indicates a wide waveform.

  FIG. 3 shows a circuit example of the overrate short pulse generator 210 shown in FIG. 2 and waveforms of signals. As shown in FIG. 3A, the over-rate short pulse generator 210 is composed of one negative logical product circuit (NAND) 211, followed by an exclusive logical sum circuit (XOR) 212, and a delay circuit 213. A data signal (“A” in the figure) and a clock signal (“B” in the figure) are supplied to the NAND circuit 211 to calculate a NAND signal 211 of the data signal and the clock. The data signal is an NRZ (Non Return to Zero) signal, and the signal pulse level is high (high) or low (low) and does not change between pulse widths as shown in FIG. 3B. The frequency of the clock signal is matched to the maximum transmission rate Bmax possible with the pass frequency bandwidth Bbpf of the bandpass filter 22 of FIG. The operation of the negative logical product of the data signal and the clock signal in the negative logical product circuit 211 generates the data of the RZ (Return to Zero) signal from the data of the NRZ signal ("C" in the figure). The RZ data output from the NAND circuit 211 is distributed to two systems ("C" and "D" in the figure), one is directly input to the exclusive OR circuit 212 in the subsequent stage, and the other is input by the delay circuit 213. The data is input to the exclusive OR circuit 212 with a delay of δ. By the operation of the exclusive OR circuit 212, short pulses are output at a frequency twice that of the clock signal within one symbol time ("E" in the figure).

  As shown in FIG. 3B, when a data signal transmission rate Br of 2.5 Gbps and a clock signal of 10 GHz are input and the delay time δ is 5 ps, a short pulse with a pulse width of 5 ps is 20 GHz within 400 ps of one symbol time. Appears at a frequency of. That is, eight short pulses are output within one symbol time. Returning to FIG. 2, this short pulse enters the band pass filter 22 in the next stage of the overrate short pulse generator 210. Since the pass frequency band Bbpf of the bandpass filter 22 is 10 GHz, the RF pulse signals generated by the bandpass filter 22 from the short pulse train output from the overrate short pulse generator 210 overlap each other. Therefore, the RF pulse signal is spread throughout the entire symbol time. The repetitive RF pulse signal described above is used. In the method, the RF pulse signals appear close to each other but appear independently. In the present invention, since the RF pulse signals overlap, the signal waveform forms one pulse within one symbol time.

  4 generates an overrate short pulse by using the overrate short pulse generator 210 (data signal transmission speed Br2.5 Gbps, clock signal 10 GHz, delay time 5 ps) shown in FIG. The waveform of the RF pulse signal generated by passing through is shown. As shown in FIG. 4, the RF pulse signal generated by the present invention has a signal waveform similar to an amplitude modulation (ASK: Amplitude Shift Keying) signal.

  When the band pass filter 22 is constituted by a Gaussian filter, the power ratio is about 3 dB when compared with the above-described repetitive RF pulse signal and the RF pulse signal of the present invention, and the effect of improving the SNR by 3 dB is obtained by the method of the present invention. It will be. Further, since the RF pulse signal of the present invention is a continuous waveform unlike the repetitive RF pulse signal, the clock can be easily extracted.

  In the above, the SNR is improved by generating a double overrate short pulse to increase the signal power of the RF pulse signal. An overrate short pulse generator capable of increasing the rate will be described. FIG. 5A shows a circuit example of an n-multiplied over-rate short pulse generator 220 that generates a 1-n-multiplied short pulse. The n-multiplied over-rate short pulse generator 220 is a multiplier that can multiply 1-n times. 221, two logical product circuits (AND) 222 and 224, and a delay circuit 223.

  The multiplier circuit 221 receives a clock signal H matched with the maximum transmission speed Bmax possible with the pass frequency bandwidth Bbpf of the bandpass filter 22 and a rate switching signal for switching the over rate, and a clock signal based on the rate switching signal. H is multiplied by n. The over rate switching by the rate switching signal can be realized, for example, by the configuration shown in the partially enlarged view of FIG. That is, the clock signal H is input to each of the circuits to be multiplied by x1 to xn, and the output is selected by the selector based on the rate switching signal (the multiplied clock signal output from the selector is multiplied by the multiplied clock). I will call it I).

  The AND circuit 222 receives the multiplied clock signal I and the data signal G output from the multiplying circuit 221 and outputs a pulse signal J obtained by AND operation. This pulse signal J is distributed to two systems, one is directly input to the subsequent AND circuit 224 and the other is input to the AND circuit 224 with a delay of δ by the delay circuit 223. By a logical product operation of the logical product circuit 224, short pulses within one symbol time are output at the frequency of the multiplied clock signal.

  The waveform of the above circuit is shown in FIG. Here, as in FIGS. 2 and 3, the data signal G is 2.5 Gbps, the clock signal H is 10 GHz, and a waveform in which a three-time overrate is performed by the rate switching signal is shown. The multiplied clock signal I is a pulse having a frequency three times that of the clock signal H (12 pulses of the multiplied clock signal I for four pulses of the clock signal H during one symbol time of 2.5 Gbps of the data signal G). Individual pulses). The pulse signal J is a waveform obtained by ANDing the multiplied clock signal I and the data signal G, and has a 30 GHz pulse train only in the portion corresponding to “1” of the data signal G. The pulse signal K has a waveform in which the pulse signal J is delayed by a delay time δ by the delay circuit 223. The overrate short pulse L is obtained by ANDing the pulse signal J and the pulse signal K.

  The over-rate short pulse generator 210 described with reference to FIGS. 2 and 3 generates a double over-rate short pulse with a simple circuit configuration. On the other hand, the n-multiplied over-rate short pulse generator 220 can generate an arbitrarily multiplied over-rate short pulse.

  Next, improvement in SNR when the overrate is increased will be described. FIG. 6 is a diagram showing an example of generating an RF pulse signal by generating double and triple overrate short pulses (2 times are shown for comparison). Also in FIG. 6, similarly to FIG. 2, the transmission speed Br of the data signal is 2.5 Gbps, and the frequency band Bbpf of the bandpass filter 22 is 10 GHz. FIG. 6 (a) is an example in which the overrate is doubled, and 8 short pulses are generated in one symbol time, and thereby an RF pulse signal is generated by a band pass filter (that is, FIG. 2 (b). )). The four waveforms in FIG. 6A show envelopes for the data signal, the overrate short pulse, the RF pulse signal before overlapping, and the waveform in which the RF pulse signal overlaps from the top (hereinafter, FIG. 6B). ) Is the same). Note that individual RF pulse signals are indicated by dotted lines in the envelope. The RF pulse signal of one symbol becomes a signal indicated by the envelope indicated by the solid line, but the swell of the envelope is eliminated by the saturated power amplifier.

  FIG. 6B is a diagram showing an example of an RF pulse signal by a triple overrate short pulse (12 short pulses are generated in one symbol time). It can be seen that the signal amplitude of the envelope of the RF pulse signal is increased at the triple overrate compared to the double overrate. For this reason, since the signal power increases three times as much as twice, the SNR is further improved. That is, as the rate is increased, the signal amplitude is increased, and the effect of improving the SNR is increased.

  Next, an example of creating the bandpass filter 22 shown in FIG. 1 will be described with reference to FIG. As shown in the left diagram of FIG. 7A, the band-pass filter 22 has microstrip lines 22b formed on an alumina substrate 22a having a ground surface 22c formed on the back surface, and between the microstrip lines 22b and between the microstrip lines 22b. And a ground pass 22c are electrically coupled to form a band pass filter. The right figure of FIG. 7A shows the pattern of the microstrip line 22b formed on the alumina substrate 22a, and the short pulse electric signal inputted from the left side is filtered and the RF pulse of the frequency component of the pass band is filtered. Output from the right as a signal.

  FIG. 7B shows the passage loss (attenuation amount when the signal passes through the filter) and the reflection loss (reflection when power is supplied from the signal source to the filter) shown in FIG. 7A. The figure shows a calculated value (dotted line) and an actual measurement value (solid line) of the ratio of the electric power to be generated, and has a performance substantially equal to the calculated value. The pass band of the band pass filter 22 is 78 to 93 GHz (bandwidth 15 GHz), and the insertion loss is 1.5 ± 0.3 dB.

  As mentioned above, although the Example of the impulse radio transmission apparatus of this invention was described, these are not limited to the above-mentioned content, In the range which does not deviate from the summary of this invention, it can implement in a various aspect.

DESCRIPTION OF SYMBOLS 10 Impulse radio | wireless transmission apparatus 20 RF transmission part 20a Data signal 20b Short pulse 20c RF pulse signal 20d RF pulse signal 21 Short pulse generator 22 Band pass filter 22a Alumina substrate 22b Microstrip line 22c Ground plane 23 Transmission amplifier 24 Antenna 30 RF reception Unit 30a RF pulse signal 30b data signal 31 antenna 32 reception amplifier 33 bandpass filter 34 detector 100 impulse radio transmission apparatus 200 RF transmission unit 200a data signal 201a clock signal 200b over rate short pulse 200c RF pulse signal 200d RF pulse signal 210 over Rate short pulse generator 211 NAND circuit (NAND)
212 Exclusive OR circuit (XOR)
213 delay circuit 220 n multiplication over rate short pulse generator 221 multiplication circuit 222 AND circuit 223 delay circuit 224 AND circuit 300a RF pulse signal 300b data signal

Claims (5)

A short pulse generator that outputs a short pulse based on the logic “1” of the data signal;
A bandpass filter that receives the short pulse and extracts an RF pulse signal in a frequency band used for communication;
A transmission amplifier for amplifying the extracted RF pulse signal;
An antenna for outputting the amplified RF pulse signal;
The short pulse generator outputs the overrated short pulse whose frequency is faster than the maximum transmission rate when the transmission rate of the data signal is slower than the maximum transmission rate that can pass through the bandpass filter. Impulse wireless transmission device. The impulse radio transmission apparatus according to claim 1, wherein the over-rated short pulse has a frequency that is twice or more the maximum transmission rate. The short pulse generator includes a NAND circuit, an exclusive OR circuit, and a delay circuit that delays for a predetermined time,
The negative logical product circuit is supplied with an NRZ data signal and a clock signal having the maximum transmission rate, and calculates a negative logical product of the data signal and the clock signal to generate RZ data. Are distributed to two systems, one is input to the exclusive OR circuit, the other is input to the exclusive OR circuit via the delay circuit, and the exclusive OR circuit calculates the exclusive OR. The impulse radio transmission apparatus according to claim 1, wherein an overrate short pulse having a frequency twice the maximum transmission rate is output. The short pulse generator includes an n-times multiplication circuit, a first AND circuit, a second AND circuit, and a delay circuit that delays for a predetermined time.
The multiplication circuit is supplied with a first clock signal having a frequency of the maximum transmission speed and an over-rate switching signal, and a second clock signal obtained by multiplying the first clock signal based on the over-rate switching signal. The first AND circuit is supplied with the NRZ data signal and the second clock signal, and calculates the logical product of the data signal and the second clock signal to generate RZ data. The RZ data is distributed to two systems, one is input to the second AND circuit, the other is input to the second AND circuit via the delay circuit, and the second AND circuit 2. The impulse radio transmission apparatus according to claim 1, wherein a logical product is calculated in step 1 and an overrate short pulse having a frequency based on the overrate switching signal is output. A short pulse generator that outputs a short pulse based on the logic “1” of the data signal, a band-pass filter that receives the short pulse and extracts an RF pulse signal in a frequency band used for communication, and the extracted RF A transmission method for an impulse radio transmission apparatus comprising: a transmission amplifier that amplifies a pulse signal; and an antenna that outputs the amplified RF pulse signal,
In the short pulse generator, when the transmission speed is lower than the maximum transmission speed that can pass through the frequency band, the overpulsed short pulse whose frequency is faster than the maximum transmission speed is output. .