CN1567732A - A novel method for receiving ultra wideband signal - Google Patents

Abstract

The invention discloses a new method for receiving ultra-wideband (UWB: UltraWideband) signals. It uses multiple parallel filters to simultaneously receive ultra-wideband signals in parallel, and the bandwidth of the signal output by the filter can be smaller than the received ultra-wideband signal. Broadband signal bandwidth, which greatly reduces the receiver's requirements for A/D sampling rate and timing (clock) accuracy, so that low-cost devices such as ordinary A/D and clock (timing) can be used to realize ultra-wideband signal The reception of the UWB system provides strong technical and cost support for the practicality of the UWB system.

Description

A New Method for Receiving UWB Signals

technical field

The invention belongs to the field of electromagnetic wave technology, such as wireless communication, radar, wired communication, etc., and particularly relates to a communication method using ultra-wideband (UWB: Ultra Wideband) signals.

Background technique

As we all know, there are two ways to define ultra-wideband (UWB: Ultra Wideband) signals:

)大于25％ Relative bandwidth (percentage bandwidth:

) greater than 25%

整体带宽大于500MHz

The overall bandwidth is greater than 500MHz

The comparison between UWB signal and narrowband signal is shown in Fig. 1.

Composition of UWB signal transmitter: UWB signal transmitter includes UWB modulator module 7 composed of modulation module 1 and pulse waveform generator module 2, radio frequency composed of amplifier a module 3, filter a module 4 and spectrum shift a module 5 Front-end module 8 and transmitting antenna 6. as shown in picture 2.

The working process of the transmitter: the information (data) vector b(t) is modulated by the modulation module 1 and the pulse waveform generator module 2 to generate a UWB signal (the bandwidth comparison diagram of the UWB signal and the narrowband (NB: Narrow Band) signal is shown in Figure 1 shown), and then input to the transmission medium through the transmitting antenna 6 through the radio frequency front-end module 8 composed of the amplifier a module 3, the filter a module 4 and the spectrum shift a module 5. The amplification gain coefficient of the amplifier a module 3 can be greater than 1 or equal to 1; the spectrum shift amount of the spectrum shift a module 5 can be set as required, or the spectrum shift amount can be zero.

In the existing ultra-wideband (UWB: Ultra Wideband) signal receiving method (technology), it can be divided into two methods: serial reception and serial-parallel hybrid reception.

The existing ultra-wideband (UWB: Ultra Wideband) signal receiving methods (techniques) include:

(1) Serial reception: This is the most common and widely used reception method in existing communication systems. As shown in FIG. 3 , the signal received by the antenna 9 and the template signal are output by the correlator, and then the demodulated signal is obtained through the integrator a module 13 and the decision module 14 . For details, see: Dr. Jeffrey Reed and Dr. Michael Buehrer, "Introduction to UWB: Impulse Radio for Radar and Wireless Communications," MOBILE & PORTABLE RADIORESEARCH GROUP, 2001.

(2) Receive signals in parallel through the delay unit group, and finally synthesize serial output: After the signal received from the antenna is processed necessary, it is received in parallel by a set of delayers, and then demodulated, and finally the demodulated Signal serial output. For details, see: M. Srinivasan C.-C. Chen G. Grebowsky and A. Gray, "An All-Digital, High Data-Rate Parallel Receiver," Communications and Systems Research Section Goddard Space Flight Center, Greenbelt, Maryland, 1997. The disadvantages of existing ultra-wideband (UWB: Ultra Wideband) signal receiving methods (techniques) are:

(1) The instantaneous bandwidth of the signal is very wide (GHz order), and the sampling rate of the A/D sampler is too high for serial reception;

(2) The requirements for timing (clock) accuracy are too high when the delay unit group is used to receive signals in parallel;

(3) The sampling rate of each parallel branch cannot be adaptively changed with the actual situation when the delay unit group is used to receive signals in parallel;

(4) The existing receivers are all synthesized serial outputs, and the data rate is too high, which brings great pressure to the post-processing;

(5) The implementation cost of the system is high;

(6) The capacity of the system is limited and does not meet the requirements of future communication systems

(7) It is not conducive to the practical and commercialization of UWB systems.

Contents of the invention

Task of the present invention is to provide a kind of receiving method of new ultra-wideband (UWB:Ultra Wideband) signal, adopts receiving method of the present invention, can greatly reduce receiver to the requirement of A/D sampling rate, timing (clock) precision, Therefore, low-cost devices such as ordinary A/D and clock (timing) can be used to receive ultra-wideband signals, which provides strong technical and cost support for the practical use of UWB systems.

As shown in Fig. 4, a kind of new receiving method of ultra-wideband signal of the present invention, comprises

The first step: (preprocessing step) receives signal r (t) from receiving antenna 9, and r (t) carries out the preprocessing of receiver front end through radio frequency receiving front end module 18, obtains signal w (t), after preprocessing The signal can better meet the processing requirements of the subsequent circuit;

It is characterized in that it also includes the following steps:

The second step: (step of setting the working frequency band of each filter) In order to receive the signal w(t) in parallel, we need to set each filter i in the filter bank (0≤i≤N-1, N is the filter bank The number of middle filter, N is the operating frequency band of natural number); Let the bandwidth of the entire UWB signal transmission frequency band be C Hz, and the method of evenly distributing the operating frequency band can be adopted, then each filter i (0≤i≤N-1) The bandwidth of the working frequency band should be C/N Hz; the method of unequally distributing the bandwidth of the transmitting frequency band can also be adopted: the bandwidth of the working frequency band of each filter in the filter bank composed of filter i (0≤i≤N-1) is also Can be different; the working frequency bands of each filter in the filter bank composed of filter i (0≤i≤N-1) are allowed to partially overlap (as shown in Figure 7), or not overlap (as shown in Figure 6 Shown); What adopted in Fig. 6 is ideal filter bank, what adopted among Fig. 7 is non-ideal filter, and the operating frequency band of each filter has partial overlapping 25;

The third step: (filter parallel receiving step) the signal w(t) obtained in the first step is received in parallel by the filter bank composed of filter i (0≤i≤N-1); that is, the filter i can only Receive signals on its working frequency band, so all signals on the entire UWB transmission band can be received in parallel by combining N filters;

The fourth step: After the third step, the signal u _i (t) obtained by each filter i is multiplied with cos(ω _it t) under the action of the multiplication module 20 to solve the corresponding filter of the signal in the frequency domain The information stored in the i working frequency band is obtained from the signal v _i (t), 0≤i≤N-1;

The fifth step: (analog-to-digital conversion step) the signal v _i (t) obtained in the fourth step is sampled by the A/D sampler module on the branch where it is located to obtain the i-th digitized signal, 0≤i≤N-1 ;

Step 6: (Integration step) The i-th digitized signal obtained in the fifth step is integrated through its corresponding integrator module i, and then channel correction is performed with the cooperation of its corresponding channel estimation module to obtain the corrected first i signal, 0≤i≤N-1;

The 7th step: (IDFT step) the corrected signals of various paths obtained by the 6th step enter the IDFT module 24 in parallel and carry out the IDFT transformation;

Step 8: Get the estimated value { ₀ ,..., _i ,..., _N-1 } of the parallel output original information (data) from the seventh step, which is the information (data) we need finally.

It should be noted:

The fourth step above is to multiply the signal u _i (t) obtained in the third step by the cos(ω _i t) through the multiplier module, and then perform the analog-to-digital conversion in the fifth step. In the design of the receiver, we can also adopt a flexible method, that is, the signal u _i (t) obtained in the third step is first converted to analog and digital, and then multiplied by the cos(ω _i t) through the multiplier module, as shown in the figure 5.

The composition of receiver part of the present invention: as shown in Figure 4, comprise: radio frequency receiving front-end module 18, synchronous module 19, filter i module (0≤i≤N-1), multiplier module 20, A/D (module digital conversion) module 21, integrator i module (0≤i≤N-1), channel estimation module 22, channel correction module 23, inverse discrete Fourier transform (IDFT: InverseDiscrete Fourier Transform) module 24; RF receiving front-end module 18 It is composed of an amplifier b module 15, a filter b module 16, and a spectrum shift b module 17.

Part of the working process of the receiver of the present invention: as shown in Figure 4, the signal received by the receiving antenna 9 in the receiver is sent to the radio frequency receiving front end composed of amplifier b module 15, filter b module 16, and spectrum shift b module 17 The module 18 obtains the signal w(t), and then w(t) is received by a filter bank composed of filters i (0≤i≤N-1) and filtered in parallel, and the filtered signal v _i (t) is multiplied Cos(ω _it t) is multiplied (0≤i≤N-1) under the action of the converter module 20, and the multiplied signal is converted into analog to digital by the A/D module. The digitized i-th signal passes through the integrator module i (0≤i≤N-1), and then undergoes channel correction with the cooperation of its corresponding channel estimation module, and finally each signal passes through the IDFT module 24 in parallel for IDFT transformation. After IDFT transformation, the estimated value { ₀ ,..., _i ,..., _N-1 } of the original information (data) is output in parallel.

It should be noted:

Wherein the amplification gain factor of the amplifier b module 15 can be greater than 1, also can be equal to 1;

The operating frequency bands of the filters in the filter bank composed of filters i (0≤i≤N-1) in the receiver are allowed to partially overlap. What used in Fig. 6 is an ideal filter bank, and what used in Fig. 7 is a non-ideal filter, and the operating frequency bands between the filters have partial overlap 25;

In the filter bank composed of filters i (0≤i≤N-1), the bandwidth of the output signal of each filter can be greater than, equal to or smaller than the bandwidth of the input signal. However, in order to reduce the requirements for the A/D sampling rate in the post-stage circuit, we should reduce the bandwidth of the signal output by the filter as much as possible;

Orthogonal frequency group {cos(ω ₀ t), ..., cos(ω _i t), ..., cos(ω _N-1 t)} in the sine wave angular frequency ω _i and filter i-1 module post-multiplier 20 The difference of the input sine wave angular frequency ω _i-1 is ω ₀ ; that is, ω _i -ω _i-1 = ω ₀ , where 0<i≤N-1;

The sampling rate of each A/D sampler module can be greater than, equal to or less than the bandwidth of the signal transmitted by the UWB transmitter received by the receiving antenna 9 . However, since we use a filter bank composed of filters i (0≤i≤N-1) to simultaneously receive ultra-wideband signals in parallel, in practical engineering applications, the sampling rate of each A/D sampler module is lower than that of the receiving antenna 9 The bandwidth of the signal transmitted by the UWB transmitter received;

The channel estimation and channel correction functions may or may not be used in the receiver.

The Inverse Discrete Fourier Transform (IDFT: Inverse Discrete Fourier Transform) module 24 in the receiver may adopt discrete Fourier transform technology; it may also adopt Fast Fourier Transform (FFT: Fast Fourier Transform) technology.

Compared with other UWB signal receiving methods (technology), the engineering realization of the present invention has the following characteristics:

(1) It greatly reduces the receiver's requirements for A/D sampling rate and timing (clock) accuracy. This is because in the filter bank composed of filters i (0≤i≤N-1), the bandwidth of the signal output by each filter can be smaller than the bandwidth of the input filter signal, which makes the A /D can adopt undersampling technology;

(2) adopt receiving method of the present invention, can utilize multi-channel parallel filter to receive ultra-wideband signal in parallel simultaneously, the signal bandwidth of filter output can be less than the bandwidth of the ultra-wideband signal that receives, and this just reduces receiver greatly. The requirements for A/D sampling rate and timing (clock) accuracy, so that low-cost devices such as ordinary A/D and clock timing can be used to receive ultra-wideband signals, providing technical and cost advantages for the practicality of UWB systems the strong support of

(3) Since the present invention uses an orthogonal frequency group {cos(ω ₀ t),..., cos(ω _it ),..., cos(ω _N-1 t)}, this enhances the system's ability to suppress fading channels ability to influence

(4) Since the position of the A/D module in the present invention is relatively forward relative to the position of the A/D module in the traditional receiver, it is beneficial to the realization of digital integration of the system;

(5) The entire receiver processes data in parallel, so that high-speed UWB signals are processed in parallel, reducing the requirements for device performance and ensuring the stability of the system;

(6) Since the orthogonal frequency groups {cos(ω ₀ t),..., cos(ω _it ),..., cos(ω _N-1 t)} and IDFT are all implemented in the receiver, it is different from the general UWB system with OFDM (equivalent IDFT in transmitter, orthogonal frequency set {cos(ω ₀ t),..., cos(ω _it ),..., cos(ω _N-1 t)} in receiver In this way, it can overcome the shortcomings of timing error, sensitivity to carrier synchronization and large peak-to-average power ratio (PAPR).

In summary, adopting the method for receiving ultra-wideband (UWB: Ultra Wideband) signals proposed by the present invention, while retaining many advantages of the original UWB system, utilizes multiple parallel filters to simultaneously receive ultra-wideband signals in parallel, The bandwidth of the signal output by the filter can be smaller than the bandwidth of the received ultra-wideband signal, which can greatly reduce the receiver's requirements for A/D sampling rate and timing (clock) accuracy, so that ordinary A/D and clock ( Timing) and other low-cost devices realize the reception of ultra-wideband signals, which provides strong technical and cost support for the practicality of UWB systems.

Drawings and Description of Drawings

Figure 1 is a schematic diagram of an ultra-wideband signal and a common narrowband signal in the frequency domain

Among them, NB is a narrowband signal: Narrow Band, UWB is an ultra-wideband signal: Ultra Wideband, f _L represents the lowest frequency of the signal, f _H represents the highest frequency of the signal, and f _C represents the center frequency of the signal.

Figure 2 is a block diagram of a common common UWB signal transmitter

Among them, 1 is the modulation module, 2 is the pulse waveform generator module, 3 is the amplifier a module, 4 is the filter a module, 5 is the spectrum shift a module, 6 is the transmitting antenna, 7 is the UWB modulator module, 8 is the radio frequency Front-end module, b(t) is the original input information.

Figure 3 is a block diagram of a traditional UWB receiver

Wherein, 9 is a receiving antenna, 10 is a correlator, 11 is a template signal, 12 is a synchronization module a, 13 is an integrator a, and 14 is a decision device.

Fig. 4 is a receiver block diagram of the present invention

Among them, 9 is a receiving antenna, 15 is an amplifier b module, 16 is a filter b module, 17 is a spectrum shift b module, 18 is a radio frequency receiving front-end module, 19 is a synchronization module, 20 is a multiplier module, and 21 is an A/D module, 22 is the channel estimation module, 23 is the channel correction module, 24 is the inverse discrete Fourier transform (IDFT: Inverse Discrete FourierTransform) module, { ₀ ,..., _i ,..., _N-1 } is the restored original Input information (data) estimated value, signal w (t) is the output signal of radio frequency receiving front-end module 18, signal u _i (t) is the output signal of filter i, signal v _i (t) is u _i (t) and The result of multiplying cos(ω _it t).

Fig. 5 is the block diagram of another form of receiver of the present invention

Among them, 9 is a receiving antenna, 15 is an amplifier b module, 16 is a filter b module, 17 is a spectrum shift b module, 18 is a radio frequency receiving front-end module, 19 is a synchronization module, 20 is a multiplier module, and 21 is an A/D module, 22 is the channel estimation module, 23 is the channel correction module, 24 is the inverse discrete Fourier transform (IDFT: Inverse Discrete FourierTransform) module, { ₀ ,..., _i ,..., _N-1 } is the restored original The estimated value of input information (data), the signal w(t) is the output signal of the radio frequency receiving front-end module 18, and the signal u _i (t) is the output signal of the filter i.

Figure 6 is a schematic diagram of non-overlapping working frequency bands in a filter bank composed of filters i (0≤i≤N-1)

Among them, the ideal filter is used in the figure. The horizontal axis represents the frequency in Hz; the vertical axis represents the magnitude of the frequency response characteristic of the filter.

Fig. 7 is a schematic diagram of partially overlapping working frequency bands in a filter bank composed of filters i (0≤i≤N-1)

Among them, the non-ideal filter is used in the figure. The horizontal axis represents the frequency, and the unit is Hz; the vertical axis represents the magnitude of the frequency response characteristic of the filter, and 25 indicates that the working frequency bands between the filters partially overlap.

Detailed ways

As shown in Figure 4, if there are 4 channels of parallel sampling, then N=4, we assume that the transmitter transmits a Gaussian pulse signal with a bandwidth of 2GHz, that is, from DC (direct current) to 2GHz. The received ultra-wideband signal is amplified with low noise through amplifier b, and then through low-pass filter b with a bandwidth of 2GHz (or slightly greater than 2GHz) for out-of-band noise suppression. Here we assume that the spectrum shift is zero, which does not loss of generality. So far, the signal preprocessing function of the radio frequency receiving front-end module 18 is completed. One output signal w(t) of the module 18 is sent to the synchronization module 19 for synchronous control, and one output signal is sent to four filters for parallel filtering. At this time, the working frequency band allocation principle of filter 0 to filter 3 can be: filter 0 is a low-pass filter from DC to 500MHz, filter 1 is a band-pass filter from 500MHz to 1GHz, and filter 2 is from 1GHz to 1.5 GHz is a band-pass filter, and filter 3 is a band-pass filter from 1.5 GHz to 2 GHz. The frequency response characteristics of each filter can be ideal in theory, as shown in Figure 6, but there are some overlaps in actual engineering , as shown in Figure 7. Next, the output signal u _i (t) of filter i is multiplied by cosω _it t, i=0,1,2,3. After the multiplication is the A/D sampling process. According to the sampling theorem of low-pass and band-pass, the sampling rate of the 4 channels is 1GHz. Of course, when allocating the working frequency bands of filter 0 to filter 3, it can also be allocated unevenly, and it can be determined according to the needs, so that the sampling rate of each A/D will be different, which can better adapt to the actual engineering situation. The digitized i-th signal is integrated by the integrator i module, and then channel correction is performed with the cooperation of the channel estimation module, and then IDFT transformation is performed, of course, it can also be a fast algorithm IFFT; finally, the estimation of the original information (data) is output in parallel Value { _0 , _1 , _2 , _3 }. The above process can be realized by programming with tool software.

Claims (2)

1, the method for reseptance of a kind of new ultra-broadband signal of the present invention comprises

The first step (pre-treatment step): receive signal r (t) from reception antenna (9), r (t) carries out the preliminary treatment of receiver front end through receiver rf front-end module (18), obtain signal w (t), pretreated signal can better satisfy the processing requirements of late-class circuit;

It is characterized in that it also comprises following step:

Second step (the working frequency range step of each filter is set): for parallel received signal w (t), we need be provided with the working frequency range of each filter i in the bank of filters (0≤i≤N-1, N are the quantity of bank of filters median filter, and N is a natural number); If whole UWB signal transmit frequency band bandwidth is CHz, can adopt the method for mean allocation working frequency range, (the working frequency range bandwidth of 0≤i≤N-1) should be C/N Hz to each filter i so; Also can adopt unequal method of distributing the transmit frequency band bandwidth: (bandwidth of the working frequency range of each filter also can be inequality in the bank of filters of 0≤i≤N-1) form by filter i; (working frequency range of each filter allows the overlapping of part in the bank of filters of 0≤i≤N-1) form, also can be not overlapping by filter i;

The 3rd step (filter parallel receive step): the signal w (t) that obtains through the first step is by by filter i (the bank of filters parallel receive of 0≤i≤N-1) form, output signal u _i(t); Be that filter i can only receive the signal on its working frequency range, so just lump together all signals on can the whole UWB emission band of parallel receive by N bank of filters;

The 4th step: after the 3rd step, the signal u (t) that is obtained by each filter i is under the effect of multiplier module (20) and cos (ω _iT) multiply each other and solve signal respective filter i working frequency range on frequency domain and deposit the information of holding, obtain signal v _i(t), 0≤i≤N-1;

The 5th step (analog-to-digital conversion step): go on foot the signal v that obtains by the 4th _i(t) through obtaining the digitized signal in i road, 0≤i≤N-1 after the sampling of A/D sampler module on its place branch road;

The 6th step (integration step): carry out integration by its corresponding integrator module i by the i road digitized signal that the 5th step obtained, under the cooperation of its corresponding channel estimation module, carry out channel correction subsequently, i road signal after obtaining proofreading and correct, 0≤i≤N-1;

The 7th step (IDFT step): enter IDFT module (24) by each the road signal parallel after the 6th correction that obtain of step and carry out the IDFT conversion;

The 8th goes on foot: go on foot by the 7th and obtain the also estimated value {  of the raw information (data) of line output ₀...,  _i...,  _N-1, our information (data) of finally needing that Here it is.

2, the method for reseptance of a kind of new ultra-broadband signal according to claim 1 is characterized in that the order in described the 4th step and the 5th step can exchange, and is about to the signal u that the 3rd step obtained _i(t) carry out analog-to-digital conversion (the 5th step) earlier, and then by multiplication module and cos (ω _iT) multiply each other (the 4th step).

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