JP6256739B2 - Wireless transmitter, wireless receiver, wireless communication system, and wireless communication method - Google Patents

Description

  The present invention relates to a wireless transmitter, a wireless receiver, a wireless communication system, and a wireless communication capable of extending a communication distance while using an ultra wide band (UWB) high-frequency pulse (ultra short pulse). It is about the method.

  As a wireless communication technique attracting attention in recent years, there is a method using an impulse type UWB that performs communication using a pulse having a very small time width (see Non-Patent Documents 1 and 2).

  In the impulse UWB communication, information is transmitted by using a pulse signal having a very short time width of about 1 nanosecond and changing the position, amplitude, or phase of the pulse signal on the time axis.

  The frequency bandwidth occupied by the UWB signal is very wide from 500 MHz to several GHz or more, but since a pulse signal with a very short time width of 1 nanosecond is used, signal transmission at a high data rate and high-precision distance measurement are used. Can be realized.

  In addition, the wireless communication method using the impulse UWB has features such as a low-power-consumption communication method as well as a low manufacturing cost because the configuration of the transceiver is simple.

Kenichi Midugaki, Tatsuo Nakagawa, Ryosuke Fujiwara, Shinsuke Kobayashi, Noboru Koshizuka, and Ken Sakamura: "UWB-IR Wireless Accurate Location System for Sensor Network," IEICE Trans.Commun., Vol.E94-B, no.5, pp. 1432-1437, May 2011. Ryosuke Fujiwara, Kenichi Midugaki, Tatsuo Nakagawa, Takayasu Norimatsu, Takahide Terada, Akira Maeki, and Masayuki Miyazaki: "Accurate TOA Estimating UWB-IR Transceiver for Ranging System in Multi-path Environment," IEICE Trans. Commun., Vol. E94- B, No.3, pp.777-785, March 2011.

  In Japan, Europe, the United States, etc., as shown in FIG. 4, the peak power density and the average power density that can be emitted by the UWB transmitter are regulated by law. FIG. 4 is a schematic diagram showing the peak power and average power of the impulse UWB. For example, in Japan, the peak power density is required to be 0 dBm / 50 MHz or less, and the average power density is required to be -41.3 dBm / MHz or less.

  Further, in Japan, the UWB frequency band that can be used without applying the interference mitigation technology is 7.25 GHz to 10.25 GHz. Therefore, there is a problem that the distance that UWB radio waves can reach is short. For this reason, for example, when positioning is performed using an impulse UWB, more positioning reference stations are required, leading to an increase in the cost of communication equipment.

  Therefore, the present invention has been devised in view of the above-described problems, and enables communication over a longer distance than before and realizes cost reduction of communication equipment by reducing the number of base stations. An object of the present invention is to provide a wireless transmitter, a wireless receiver, a wireless communication system, and a wireless communication method using an impulse UWB that can be used.

  In order to solve the above-described problems, the present inventor enables long-distance communication using an impulse UWB, and reduces the number of positioning reference stations when performing positioning using the impulse UWB. Have invented a wireless transmitter, a wireless receiver, a wireless communication system, and a wireless communication method that can realize low cost.

A radio transmitter according to a first aspect of the present invention is a radio transmitter using an impulse UWB, which modulates transmission data and generates a transmission digital signal in parallel with the baseband signal processing unit. The transmission digital signal transmitted from the baseband signal processing unit is provided between a plurality of transmission units that convert each of the transmission digital signals into impulse UWB signals having the same peak power density and two adjacent transmission units. A delay circuit that shifts the transmission timing of the impulse UWB signals transmitted from a plurality of the transmission units , and a transmission antenna that is connected to each of the plurality of transmission units and transmits the impulse UWB signals, The number of transmitters is such that the sum of the power of the impulse UWB signal generated by the transmitter exceeds a predetermined threshold of average power density. Characterized in that it is set in the stomach area.

A radio communication system according to a second aspect of the present invention is a communication system comprising a transmitter and a receiver that use impulse UWB, wherein the transmitter modulates transmission data and generates a transmission digital signal. A baseband signal processing unit and a plurality of transmission digital signals connected in parallel to the baseband signal processing unit , each of which converts the transmission digital signal transmitted from the baseband signal processing unit into an impulse UWB signal having the same peak power density . A transmission circuit, a delay circuit provided between two adjacent transmission units and configured to shift transmission timings of the impulse UWB signals transmitted from the plurality of transmission units; and the impulse UWB respectively connected to the plurality of transmission units. A transmission antenna for transmitting a signal, and the number of the transmission units is the impulse generated by the transmission unit. The total power of the WB signal is set in a range that does not exceed a predetermined limit value of the average power density, and the receiver includes a plurality of antennas that receive the impulse UWB signal from the transmitter, and a plurality of antennas. A plurality of receivers connected to each other to perform low noise amplification and envelope detection of the impulse UWB signal; and an adder that connects all of the plurality of receivers and generates a composite wave based on the result of the envelope detection; It is characterized by having.

A wireless communication method according to a third aspect of the present invention is a wireless communication method that performs wireless transmission and reception using impulse UWB, and in the wireless transmission, a baseband signal processing step that modulates a transmission digital signal; A division step of dividing the transmission digital signal into a plurality of transmission signals of the same strength, a delay step of shifting the transmission timing of the transmission digital signal divided in the division step, and the plurality of timings shifted by the delay step a transmission digital signal, a transmission step of transmitting the converted equal the impulse UWB signals of peak power density, is carried out, and in the radio receiving, receiving said plurality of impulse UWB signal transmitted in the transmission step And an addition process for obtaining a composite wave by adding the plurality of impulse UWB signals received in the reception step. The number of divisions in the transmission step is set in a range in which the sum of the powers of the plurality of impulse UWB signals transmitted in the transmission step does not exceed a predetermined limit value of the average power density. And

  According to the present invention having the above-described configuration, it is possible to perform long-distance communication using an impulse UWB, and it is possible to reduce the cost of communication equipment by reducing the number of base stations.

It is a schematic diagram which shows the wireless transmitter which concerns on embodiment of this invention. It is a schematic diagram which shows the radio receiver which concerns on embodiment of this invention. It is a flowchart which shows the process performed by the radio | wireless transmitter and radio | wireless receiver which concern on embodiment of this invention. It is a schematic diagram which shows the peak power and average power of impulse type UWB.

  Hereinafter, a wireless communication system including a wireless transmitter and a wireless receiver will be described in detail as an embodiment of the present invention.

  FIG. 1 is a schematic diagram showing a wireless transmitter 2 according to an embodiment of the present invention. The wireless transmitter 2 includes a baseband signal processing unit 21, a four-stage transmission unit 22 connected in parallel to the baseband signal processing unit 21, a baseband signal processing unit 21, and second-stage and subsequent transmission units 22. And a transmission antenna 24 connected to the transmission unit 22 and transmitting an impulse UWB signal.

  The baseband signal processing unit 21 modulates transmission data and generates a transmission digital signal. Any modulation method of the transmission digital signal can be adopted, and for example, pulse density modulation can be used. The transmission digital signal thus generated is a pulse A that is a rectangular digital signal as shown in FIG. 1, and is sent to a plurality of transmission units 22 that are connected in parallel to the baseband signal processing unit 24. Sent out.

  Four transmitters 22 are arranged in parallel in the wireless transmitter 2. The transmission unit 22 amplifies the pulse A, which is a transmission digital signal transmitted from the baseband signal processing unit 21, and converts the pulse A into an impulse UWB signal. In addition, the transmission unit 22 limits the band used for transmission of the impulse UWB signal. The impulse UWB signal thus generated by the transmission unit 22 is transmitted via the transmission antenna 24.

  Further, a delay circuit 23 is provided between the baseband signal processing unit 21 and the second and subsequent transmission units 22. The delay circuit 23 has a function of shifting the transmission timings of the impulse UWB signals transmitted from the four transmission units 22 via the transmission antenna 24. In the present embodiment, a total of three delay circuits 23 are provided between the baseband signal processing unit 21 and the second-stage, third-stage, and fourth-stage transmission sections 22.

  By the function of the delay circuit 23, the wireless transmitter 2 is transmitted at the pulse B1 transmitted at the transmission timing t1, the pulse B2 transmitted at the transmission timing t2, the pulse B3 transmitted at the transmission timing t3, and the transmission timing t4. It is possible to transmit four impulse UWB signals having different transmission timings of the pulse B4.

  The pulses B1, B2, B3, and B4 differ only in transmission timing, and the average power density, peak power density, and information included in these are common.

  In this way, four pulses B1, B2, B3 and B4 whose transmission timings are shifted from each other are transmitted from the wireless transmitter 2, and this is a combination of the four pulses B1, B2, B3 and B4 shown in FIG. This is synonymous with the transmission of the general impulse component C.

  Although the total impulse component C has the same pulse intensity (peak power) as the original pulse A and pulses B1, B2, B3, and B4, the transmission average power density is theoretically four times. For this reason, it is possible to extend the distance at which the UWB signal can be transmitted.

  By the way, when performing wireless communication, depending on the frequency of repetition of pulses (PRF: Pulse Repetition Frequency), the influence of any one of the above-described limitations on the average power density and the peak power density becomes large.

  Specifically, when the PRF is small, the limitation due to the peak power density becomes dominant, and when the PRF is large, the limitation on the average power density becomes dominant.

  That is, when the PRF is small, the number of pulses is small, and the average power density obtained based on the sum of the power of each pulse is small. Therefore, it is unlikely that the limit value of the average power density will be exceeded. The limitation is a bigger problem.

  On the other hand, when the PRF is large, the number of pulses is large, and the average power density obtained based on the sum of the powers of the pulses increases, so that the possibility of exceeding the limit value of the average power density increases. Therefore, the limitation of the average power density becomes a big problem.

  When performing low-speed communication, ranging, etc. using impulse type UWB, the PRF is small, so the limitation due to the peak power density becomes dominant, even if the peak power density reaches 0 dBm / 50 MHz. The average power density is likely not to reach -41.3 dBm / MHz.

  Therefore, in the wireless transmitter 2 according to the present embodiment, the average power density does not reach -41.3 dBm / MHz by increasing the number of the transmission units 22 while keeping the peak power density below 0 dBm / 50 MHz. The average power density of the total impulse component C is increased within the range. That is, the average power density of the total impulse component C is doubled according to the number of transmission units 22.

  According to the transmitter 2 according to this embodiment, the total transmission power can be increased and the communicable distance can be increased by increasing the average power density while keeping the peak power density below 0 dBm / 50 MHz. be able to.

  FIG. 2 is a schematic diagram showing the wireless receiver 3 according to the embodiment of the present invention. The wireless receiver 3 includes four receiving antennas 31 that receive the impulse UWB signal transmitted from the wireless transmitter 2, four receiving units 32 connected to the receiving antenna 31, and four receiving units 32. All of the adders 33 are connected to each other.

  The receiving antenna 31 receives the total impulse component C transmitted from the wireless transmitter 2 and transmits the received total impulse component C to the receiving unit 32.

  The receiving unit 32 functions as a low noise amplifier and performs envelope detection of the amplified signal. That is, the receiving unit 32 performs low noise amplification on the received total impulse component C, detects the envelope after amplification, and transmits the envelope detection output to the adder 33.

  The adder 33 adds the four envelope detection outputs received from the four receivers 32 to generate a synthesized wave D. Compared with the total impulse component C, the power of the combined wave D theoretically doubles according to the number of receiving units 32. In this embodiment, since the number of receiving units 32 is four, the power is also quadrupled.

  Therefore, since the combined received power can be increased on the wireless receiver 3 side for the total impulse component C transmitted from the wireless transmitter 2, wireless communication over a longer distance than before can be realized. The synthesized wave D generated in this way is subjected to further processing such as AD conversion in the radio receiver 2.

  Next, wireless communication performed by the wireless transmitter 2 and the wireless receiver 3 described above will be described. FIG. 3 is a flowchart showing processing performed by the wireless transmitter 2 and the wireless receiver 3 according to the embodiment of the present invention.

  First, the baseband signal processing unit 21 of the wireless transmitter 2 modulates transmission data and generates a rectangular pulse A, which is a transmission digital signal, as a transmission signal (step S1).

  Next, the generated pulse A is divided and transmitted toward the transmitters 22 arranged in parallel (step S2).

  Next, the transmission timing of the pulse A transmitted from the baseband signal processing unit 21 toward the transmission unit 22 by the delay circuit 23 provided between the baseband signal processing unit 21 and each transmission unit 22 is determined. It is shifted at a predetermined interval (step S3).

  Next, when receiving each pulse A, the transmission unit 22 converts the pulse A into an impulse UWB signal, and transmits the converted signal via the transmission antenna 24 (step S4).

  In the present embodiment, as described above with reference to FIG. 1, the pulses B1, B2, B3, and B4 are transmitted from the four transmission units 22 through the four transmission antennas 24, respectively. Is synonymous with transmission of a comprehensive impulse component C.

  When the transmission of the comprehensive impulse component C is thus completed, the wireless transmitter 2 ends the operation.

  On the other hand, the radio receiver 3 first waits for a signal transmitted from the radio transmitter 2 (step S11).

  Next, the wireless receiver 3 receives the comprehensive impulse component C transmitted from the wireless transmitter 2 (step S12). Specifically, the four receiving antennas 31 of the wireless receiver 3 each receive the total impulse component C and are transmitted to the receiving unit 32.

  The four receiving units 32 that have received the comprehensive impulse component C perform low-noise amplification on this, perform envelope detection of the amplified signal, and detect the detected envelope (the broken line of the total impulse component C is a broken line). Information) is transmitted to the adder 33.

  Next, the adder 33 receives the envelope information of the total impulse component C transmitted from each receiving unit 32, and all the total received by the wireless receiver 3 based on the information of the envelope. The impulse component C (four in this embodiment) is added to generate a composite wave D (step S13). The synthesized wave D generated in this way is subjected to further processing inside the radio receiver 3.

  By the way, the generated synthetic wave D theoretically has a peak power density that is theoretically four times as large as the total impulse component C transmitted from the wireless transmitter 2 to the wireless receiver 3. However, since the synthesized wave D is used only in the wireless receiver 3 and is not transmitted in the air, it is not restricted by the restriction of the peak power density.

  Further, the average power density of the composite wave D is theoretically four times that of the total impulse component C, which is 16 in comparison with the pulses B1, B2, B3, and B4 transmitted from the individual transmitters 22 of the wireless transmitter 2. However, this is also used only for processing in the wireless receiver 3 and is not transmitted in the air, so that it is not restricted by the regulation of the average power density.

  Therefore, for the communication using the impulse UWB, which has a low power density and was conventionally able to perform only a short-distance communication, the communication distance can be extended and the wireless transmitter 2 required for maintenance of the communication network The number of radio receivers 3 can be reduced, and the cost of communication equipment can be reduced.

  In the wireless communication system according to the present embodiment described above, the wireless transmitter 2 is provided with four transmitters 22 and the wireless receiver 3 is also provided with four receivers 32.

  However, the present invention is not limited to this, and an arbitrary number of transmission units 22 may be provided within a range in which the total impulse component C transmitted between the wireless transmitter 2 and the wireless receiver 3 does not exceed the regulation value of the average power density. Can be provided. Further, any number of receivers 32 can be provided regardless of the regulation value of the average power density.

2 Radio transmitter 3 Radio receiver 21 Baseband signal processor 22 Transmitter 23 Delay circuit 24 Transmitting antenna 31 Receiving antenna 32 Receiver 33 Adder A, B1, B2, B3, B4 Pulse C Total impulse component D Synthesis wave

Claims (3)

A wireless transmitter using impulse UWB,
A baseband signal processing unit that modulates transmission data and generates a transmission digital signal;
A plurality of transmission units connected in parallel to the baseband signal processing unit and converting the transmission digital signals transmitted from the baseband signal processing unit into impulse UWB signals each having the same peak power density ;
A delay circuit that is provided between two adjacent transmission units and shifts the transmission timing of the impulse UWB signal transmitted from the plurality of transmission units;
A transmission antenna connected to each of the plurality of transmission units and transmitting the impulse UWB signal;
And the number of the transmission units is set in a range in which the total power of the impulse UWB signal generated by the transmission unit does not exceed a predetermined limit value of the average power density. . A communication system comprising a transmitter and a receiver using impulse UWB, wherein the transmitter is
A baseband signal processing unit that modulates transmission data and generates a transmission digital signal;
A plurality of transmission units connected in parallel to the baseband signal processing unit and converting the transmission digital signals transmitted from the baseband signal processing unit into impulse UWB signals each having the same peak power density ;
A delay circuit that is provided between two adjacent transmission units and shifts the transmission timing of the impulse UWB signal transmitted from the plurality of transmission units;
A transmission antenna connected to each of the plurality of transmission units and transmitting the impulse UWB signal;
And the number of the transmission units is set in a range in which the total power of the impulse UWB signal generated by the transmission unit does not exceed a predetermined limit value of an average power density,
A plurality of antennas for receiving the impulse UWB signal from the transmitter;
A plurality of receiving units connected to the plurality of antennas for performing low noise amplification and envelope detection of the impulse UWB signal;
All of the plurality of receiving units are connected, and an adder that generates a composite wave based on the result of the envelope detection;
A wireless communication system comprising: A wireless communication method for performing wireless transmission and reception using an impulse UWB, wherein the wireless transmission includes:
A baseband signal processing step of modulating transmission data and generating a transmission digital signal;
A division step of dividing the transmission digital signal into a plurality of transmission signals of the same strength;
A delay step of shifting the transmission timing of the transmission digital signal divided in the division step;
A transmission step of converting the plurality of transmission digital signals shifted in timing by the delay step into impulse UWB signals having the same peak power density and transmitting the signals , respectively;
In the wireless reception,
A receiving step of receiving the plurality of impulse UWB signals transmitted in the transmitting step;
An adding step of adding the plurality of impulse UWB signals received in the receiving step to obtain a composite wave;
The number of divisions in the transmission step is set in a range in which the sum of the powers of the plurality of impulse UWB signals transmitted in the transmission step does not exceed a predetermined limit value of the average power density. Wireless communication method.

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