JP2006174254A - Fading simulator, frequency selective fading simulator and information output program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate, by using a small-scale circuit, a plurality of complex signals with no mutual relation for constituting a fading simulator channel. <P>SOLUTION: In a fading simulator, a readout address generating circuits 3121 to 312M retrieves a waveform from each of waveform storage tables 3111 to 311M at a given rate to obtain sinusoidal waves of quadrature frequencies f1 to fM. The switch circuit 3130 selects alternatively the sinusoidal wave to perform frequency hopping, thus obtaining a complex signal 11 (Q1). The other complex signal generating circuits 312 to 31N obtain equally complex signals I2 to IN (Q2 to QN). N pieces of an incoming constituent wave are simulated by using the complex signals (I1, Q1) to (IN to QN). An adding circuit 32 multiplexes the complex signals (I1, Q1) to (IN to QN) to obtain complex signals 3I, 3Q generated by modeling a frequency unselective multipath fading environment. Thus, a freedom degree of selecting the N pieces of the incoming constituent wave is substantially improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technology for simulating a multi-path fading environment of a mobile station in a baseband band, and in particular, improves the degree of freedom of setting the number of incoming elementary waves and representative frequencies and enables simulation with various models with a small circuit configuration. It relates to the technology.

  A simulator that simulates multipath fading generally operates in a radio frequency band. However, as described in Patent Document 1, an equivalent complex base is used to directly evaluate a baseband signal processing unit. A simulator that takes the form of operating in a band has been proposed.

  The simulator described in the same document propagates based on the principle that fading occurs when N elementary waves with no propagation delay time difference arrive at the mobile station and each incoming elementary wave undergoes Doppler shift of the mobile station. Model and simulate the environment.

  The simulator will be briefly described with reference to the reference numeral of FIG. 1 in the same document. The input complex signals 1 a and 1 b are sampled by the sampler 2. The fading complex amplitude generators 4a and 4b for the I channel component (COS component) and the Q channel component (SIN component) are each composed of N sequences, and complex amplitudes are read from the tables 411 and 421 in each sequence. The read complex amplitudes are added by the adders 5a and 5b, whereby the I channel component 6a and the Q channel component 6b of the fading complex amplitude are generated. N is the number of incoming waves.

  In the non-frequency-selective equivalent baseband based on the above model, the sampled input complex signals 3a and 3b and the I channel component 6a and Q channel component 6b of the fading complex amplitude are complex multiplied by the complex multiplier 7. Fading simulation outputs 8a and 8b are generated.

As shown in FIG. 3 in the same document, non-frequency selective equivalent baseband fading simulators 141 to 14M corresponding to the fading complex amplitude generator 4 are paralleled in M series, and the input stages of the simulators 141 to 14M are parallel to each other. Further, by arranging the delay circuits 121 to 12M, it is possible to simulate frequency selective fading with M representative frequencies.
JP-A-6-140950

  Referring to FIGS. 1 and 3 of Patent Document 1, according to the conventional technique described in the same document, the fading complex signal generator 4 or the non-frequency selective equivalent baseband simulators 141 to 14M include The same number of uncorrelated channels as the number N of incoming elementary waves is required. At this time, it takes a form of securing a plurality of channels by generating complex signals with initial phases shifted in fading complex signals 4a and 4b. However, in this form, there is a limit to securing the number of channels, so that a model is constructed. There was a problem that the degree of freedom was hindered.

  In view of such circumstances, it is an object of the present invention to provide a technique capable of generating a large number of complex signals that are not correlated with each other to form a channel of a fading simulator with a small circuit.

In order to solve the above-mentioned problems, the invention described in claim 1 provides a fading simulator comprising the following means.
(1) Complex signal generating means for generating a plurality of complex signals having a waveform simulating an elementary wave subjected to Doppler shift and having orthogonal frequencies.
(2) Complex signal processing means for generating a plurality of complex signals having orthogonality and having no spectral bias by exchanging a plurality of complex signals generated by the complex signal generating means of (1) with a predetermined time unit. .
(3) A superimposing unit that superimposes the complex signal generated by the complex signal processing unit of (2) to generate a complex signal that simulates a non-frequency selective multipath fading environment.

The invention according to claim 2 provides a fading simulator comprising the following means.
(1) Complex signal generating means for generating a plurality of complex signals having a waveform simulating an elementary wave subjected to Doppler shift and having orthogonal frequencies.
(2) Complex signal processing means for generating a plurality of complex signals having orthogonality and having no spectral bias by exchanging a plurality of complex signals generated by the complex signal generating means of (1) with a predetermined time unit. .
(3) Multiplication means for multiplying a plurality of complex signals generated by the complex signal processing means of (2) by orthogonal codes.
(4) A superimposing unit that superimposes a plurality of complex signals generated by the multiplying unit of (3) and generates a complex signal that simulates a non-frequency selective multipath fading environment.

According to a third aspect of the present invention, there is provided a frequency selective fading simulator comprising the following means.
(1) A plurality of fading simulators according to claim 1 or 2, wherein a plurality of representative frequencies selected from frequency bands to be simulated are assigned.
(2) Superimposing means for superimposing simulated outputs of a plurality of fading simulators to generate a complex signal simulating a frequency selective multipath fading environment.

According to a fourth aspect of the present invention, there is provided an information output program that causes an information processing terminal to execute the next step.
(1) A step of generating a plurality of complex signals having a waveform simulating an elementary wave subjected to Doppler shift and having frequencies orthogonal to each other.
(2) A step of generating a plurality of complex signals having orthogonality and having no spectrum bias by exchanging the plurality of complex signals generated in the step of (1) with each other in a predetermined time unit.
(3) A step of superimposing the complex signal generated by the step of (2) to generate a complex signal simulating a non-frequency selective multipath fading environment.

The invention according to claim 5 provides an information output program which causes an information processing terminal to execute the next step.
(1) A step of generating a plurality of complex signals having a waveform simulating an elementary wave subjected to Doppler shift and having frequencies orthogonal to each other.
(2) A step of generating a plurality of complex signals having orthogonality and having no spectrum bias by exchanging the plurality of complex signals generated in the step of (1) with each other in a predetermined time unit.
(3) A step of multiplying the plurality of complex signals generated by the step (2) by orthogonal codes.
(4) A step of superimposing a plurality of complex signals generated in the step of (3) to generate a complex signal simulating a non-frequency selective multipath fading environment.

  According to the present invention, a plurality of complex signals having a waveform simulating an elementary wave subjected to Doppler shift are generated at frequencies orthogonal to each other, and the complex signals are mutually orthogonally exchanged in a time division manner. In addition, a plurality of complex signals having no spectrum bias are obtained. Therefore, the upper limit of the number of complex signals depends on the set number of orthogonal frequencies, and since this set number can be selected with a high degree of freedom, an improvement in the degree of freedom in setting the number of complex signals is realized, and the circuit It is possible to simulate a large number of incoming elementary waves without increasing the scale.

  Further, according to the present invention, it is possible to acquire a larger number of orthogonal complex signals by multiplying a plurality of generated complex signals by orthogonal codes, and there is an advantage that the degree of freedom in setting the number of complex signals is further improved. is there.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a fading simulator according to an embodiment of the present invention. As shown in the figure, the input terminal 1 is a terminal to which input complex data 1I and 1Q are input. The sampling circuit 2 is a circuit that samples input complex data 1I and 1Q and generates and outputs sampling data 2I and 2Q. The fading complex signal generation circuit 3 is a circuit that generates fading complex signals 3I and 3Q that simulate a fading environment. The complex multiplication circuit 4 (4-1, 4-2) is a circuit that generates and outputs simulator outputs 4I and 4Q by complex multiplication of the sampling data 2I and 2Q and the fading complex signals 3I and 3Q. The output terminal 5 is a terminal for outputting the simulator outputs 4I and 4Q to the outside.

  The operation of this fading simulator will be described with reference to FIG. The input complex data 1I and 1Q are a real component and an imaginary component of the input complex signal, respectively. In this specification, the code relating to the complex signal is distinguished by attaching I to the code relating to the real part component and attaching Q to the code relating to the imaginary part component. The sampling circuit 2 samples the input complex data 1I and 1Q to generate sampling data 2I and 2Q. Then, the fading complex signal generation circuit 3 generates simulator outputs 4I and 4Q by performing complex multiplication according to equations (1) and (2) based on the sampling data 2I and 2Q and the fading complex signals 3I and 3Q.

4I = 2I × 3I−2Q × 3Q (1)
4Q = 2I × 3I + 2Q × 3Q (2)

  The fading complex signals 3I and 3Q are signals that model a non-frequency selective multipath fading environment, and are generated by the fading complex signal generation circuit 3.

  Here, the fading complex signal generation circuit 3 includes a real part component generation unit and an imaginary part component generation unit that generate a real part component and an imaginary part component of the complex signal, respectively. Since the real part component generation unit and the imaginary part component generation unit can be constructed with the same circuit configuration, the real part component generation unit will be described in detail here as an example.

  FIG. 2 is a block diagram showing a specific example of the real part component generation unit. The complex signals in the figure are all signals related to the real part component. As shown in the figure, the real part generation unit 3-1 includes N complex signal generation circuits 311, 312,... 31N that generate complex signals simulating the incoming elementary wave to the mobile station to be simulated, and each complex signal. Are added together and output as a fading complex signal 3I.

  The complex signal generation circuit 311 includes M waveform storage tables 3111, 3112... 311 M, M read address generation circuits 3121, 3122, 312 M, and a switch circuit 3130. In the description of the embodiment of the present invention, M is an integer satisfying N ≦ M. The waveform storage tables 3111, 3112,... 311M are tables each storing a waveform (complex amplitude) for one period. The read address generation circuits 3121, 3122,... 312M are circuits that generate and output read addresses to the waveform storage tables 3111, 3112,.

  The switch circuit 3130 selects any one of the read data from the respective waveform storage tables 3111, 3112... 311M and outputs the selected data to the adder circuit 32 as a generation output of the complex signal generation circuit 311. The other complex signal generation circuits 312 to 31N have the same configuration.

  Next, the operation of the complex signal generator will be described with reference to FIG. As shown in the figure, the real component generation unit 3-1 includes N complex signal generation circuits 311, 312,... 31N and an addition circuit 32. First, the complex signal generation circuit 311 will be described as an example. The read address generation circuits 3121, 3122... 312M transfer waveforms from the waveform storage tables 3111, 3112. Read with. As a result, sine waves of orthogonal frequencies f1, f2... FM are read from the respective waveform storage tables 3111, 3112. FIG. 3 is a graph showing the orthogonal frequencies f1, f2,... FM. As shown in the figure, the orthogonal frequencies f1, f2,..., FM are distributed with a separation frequency Δf apart from the representative frequency f as a center frequency.

  The switch circuit 3130 is given a selection instruction from a control device (not shown) according to an output pattern for performing frequency hopping, and the orthogonal frequencies f1, f2 read from the waveform storage tables 3111, 3112... 311M based on this selection instruction. ... Select one of the sine waves of fM and output it to the adder circuit 32 as the complex signal I1 generated by the complex signal generation circuit 311. The other complex signal generation circuits 312 to 31N execute the same processing, and output any one of the sine waves of the orthogonal frequencies f1, f2,... FM to the addition circuit 32 as the complex signal I2 ... IN generated by the complex signal generation circuit. To do.

  At this time, the control device generates an output pattern in which the same frequency is not duplicated as the output of each complex signal generation circuit 311, 312,... 31N, and gives a selection instruction to each switch circuit 3130, 3230. Further, the selection instruction is changed based on a new output pattern in a set time unit. Accordingly, the complex signals I1, I2,... IN perform frequency hopping in the range of orthogonal frequencies f1, f2,. Therefore, the complex signals I1, I2... IN are always orthogonal to each other because they are any of the frequencies f1, f2... FM at an arbitrary time, and converge to the fundamental frequency f when averaged.

  It is possible to simulate N incoming elementary waves using such complex signals I1, I2... IN, and by adding the complex signals I1, I2. It is possible to generate a fading complex signal 3I that models a path fading environment. Similarly, the imaginary component generation unit 3-2 generates complex signals Q1, Q2,... QN by the complex signal generation circuits 311, 312,... 31N, and adds the complex signals Q1, Q2,. A fading complex signal 3Q is generated. The fading complex signals 3I and 3Q obtained in this way are output to the adder circuit 4 and used to obtain the simulator outputs 4I and 4Q as described above.

  As described above, according to this embodiment, N orthogonal complex signals are generated by frequency hopping M orthogonal frequencies f1, f2,... FM. There is an advantage that the degree of freedom of selection is greatly improved.

  Next, another embodiment of the present invention will be described. FIG. 4 is a block diagram showing another specific example of the fading complex signal generation circuit. The fading complex signal generation circuit 3 can also be realized by a configuration including a pair of units shown in FIG. 4 for the I channel component and the Q channel component. The same parts as those in FIG. 4, complex signals I1, I2,... IN output from the complex signal generation circuits 311, 312,... 31N are input to the vector operation circuit 33 instead of the adder circuit 32 (see FIG. 2).

  The vector operation circuit 33 takes a form in which a larger number of complex signals are generated by performing a vector operation using orthogonal codes on the complex signals I1, I2,. As the orthogonal code, for example, a Walsh code can be used. That is, it is possible to use a form of determinant calculation obtained by substituting “−1” for the “0” term of H2p determined by equations (3) and (4).

  Complex signals I 1, I 2,... IN are used as input vectors, and vector operations are performed using a determinant HN with 2p = N, whereby complex signals FI 1, FI 2,. The obtained complex signals FI1, FI2,... FIN can be used as fading complex signals 3I each modeling a non-frequency selective multipath fading environment. That is, according to the fading complex signal generation circuit 3 according to this embodiment, N fading complex signals 3I and 3Q can be generated.

  FIG. 5 is a block diagram showing a fading simulator according to another embodiment of the present invention. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals as those in FIG. As shown in FIG. 2, the delay unit 6 is a circuit that delays the sampling data 2I and 2Q, and includes M delay circuits 61 to 6M each having a predetermined delay time. Each of the delay circuits 61 to 6M generates and outputs delay data (61I, 61Q), (62I, 62Q)... (6MI, 6MQ), respectively.

  The fading simulator unit 7 includes M fading simulator units 71 to 7L that respectively simulate the fading environment related to the representative frequency F. L is the number of representative frequencies. Each of fading simulator units 71 to 7L has the same circuit configuration unit as fading complex signal generation circuit 3 and complex multiplication circuit 4 shown in FIG. 1, and generates fading complex signals 3I and 3Q (see FIG. 1) and delays them. The outputs (71I, 71Q), (72I, 72Q),... (7LI, 7LQ) are generated by complex multiplication with the data (61I, 61Q), (62I, 62Q)... (6LI, 6LQ). The adder circuit 8 (8-1, 8-2) adds the outputs 71I, 72I... 7LI to generate the simulator output 8I, and adds the outputs 71Q, 72Q. This is a circuit for outputting the addition result as 8Q.

  FIG. 6 is a graph showing an example of selecting a representative frequency. As shown in the figure, the orthogonal frequencies F1, F2,... FL can be selected as representative frequencies and assigned to the respective fading simulator units 71 to 7L. Further, in each fading simulator unit 71 to 7L, when exemplified by the fading simulator unit 7k, M orthogonal frequencies fk1, fk2,... FkM having the representative frequency Fk as the center frequency are set in a range of ± ΔF / 2 of the representative frequency Fk. Just keep it.

  According to this embodiment, for each of the representative frequencies F1 to FL, simulation is executed by the same method as the simulator of the non-frequency selective multipath fading environment shown in FIG. It becomes possible to perform multipath fading simulation of frequency selectivity in a frequency band ranging from ~ FL. Further, it is of course possible to employ the form in which the fading simulator of FIG. 6 is configured using the fading complex signal generation circuit shown in FIG.

  The embodiment of the present invention has been described in detail above, but the specific configuration is not limited to this embodiment, and includes a design and the like within a range not departing from the gist of the present invention. For example, the fading complex signal generation circuit 3 and complex multiplication circuit 4 shown in FIG. 1, or the delay unit 6, fading simulator unit 7, addition circuit 8 and the like shown in FIG. However, such a logic circuit can also be configured using an FPGA (Field Programmable Gate Array). Further, a configuration in which a CPU type arithmetic circuit such as a DSP (Digital Signal Processor) is used may be employed.

  Here, the program to be given to the CPU type arithmetic circuit can be recorded and distributed on a computer-readable recording medium, and may be distributed in a form that realizes a part of the functions. For example, it is possible to take a form provided in the form of a so-called differential program, which can realize a predetermined function in combination with a program already recorded in the system. The computer-readable recording medium includes a storage device such as a hard disk and other nonvolatile storage devices in addition to a storage medium such as a portable magnetic disk and a magneto-optical disk. Furthermore, the form provided from another computer system via arbitrary transmission media, such as the internet and other networks, may be sufficient. In this case, the “computer-readable recording medium” includes a medium that holds a program for a certain period of time in a transmission medium such as a volatile memory inside a computer system serving as a host or client on a network.

  Further, in the form of building the above-described logic circuit by incorporating predetermined circuit information into the FPGA, it is also included in the present invention that the circuit information is distributed in the same form as the above-described program.

It is a block diagram which shows the fading simulator which concerns on one Embodiment of this invention. It is a block diagram which shows one specific example of a fading complex signal generation circuit. It is a graph which shows orthogonal frequency f1, f2, ... fM. It is a block diagram which shows the other specific example of a fading complex signal generation circuit. It is a block diagram which shows the fading simulator which concerns on other embodiment of this invention. It is a graph which shows the example of selection of a representative frequency.

Explanation of symbols

  1: Input terminal 1I, 1Q: Input complex data 2: Sampling circuit 2I, 2Q: Sampling data 3: Fading complex signal generation circuit 3-1: Real component generation unit 3-2: Imaginary component generation unit 311, 312. 31N: Complex signal generation circuit 3111 to 311M, 3211 to 321M, 3N11 to 3N1M: Waveform storage table 3121 to 312M, 3221 to 322M, 3N21 to 3N2M: Read address generation circuit 3130 to 3N30 ... Switch circuit 32: Addition circuit 33: Vector Arithmetic circuit 3I, 3Q: Fading complex signal 4 (4-1, 4-2): Complex multiplier circuit 4I, 4Q: Simulated output 5: Output terminal 6: Delay unit 61-6L: Delay circuit (61I, 61Q), (62I, 62Q) (6LI, 6LQ): Delay data 7, 7 1 to 7L: Fading simulator section 8, 8-1, 8-2: Addition circuit 8I, 8Q ... Simulator output

Claims (5)

A complex signal generating means for generating a plurality of complex signals having frequencies orthogonal to each other, simulating an elementary wave subjected to Doppler shift;
Complex signal processing means for generating a plurality of complex signals having orthogonality and having no spectral bias by exchanging the plurality of complex signals with each other in a predetermined time unit;
A fading simulator comprising: a superimposing unit that superimposes the complex signal generated by the complex signal processing unit and generates a complex signal simulating a non-frequency selective multipath fading environment. A complex signal generating means for generating a plurality of complex signals having frequencies orthogonal to each other, simulating an elementary wave subjected to Doppler shift;
Complex signal processing means for generating a plurality of complex signals having orthogonality and having no spectral bias by exchanging the plurality of complex signals with each other in a predetermined time unit;
Multiplying means for multiplying a plurality of complex signals generated by the complex signal processing means by orthogonal codes;
A fading simulator comprising: a superimposing unit that superimposes a plurality of complex signals generated by the multiplication unit and generates a complex signal simulating a non-frequency selective multipath fading environment. A plurality of fading simulators according to claim 1 or 2, wherein a plurality of representative frequencies selected from frequency bands to be simulated are assigned,
A frequency selective fading simulator comprising: a superimposing unit that superimposes simulated outputs of the plurality of fading simulators and generates a complex signal simulating a frequency selective multipath fading environment. A waveform simulating an elementary wave subjected to Doppler shift, and generating a plurality of complex signals having frequencies orthogonal to each other;
Replacing a plurality of complex signals generated by the step with each other in a predetermined time unit to generate a plurality of complex signals having orthogonality and having no spectral bias; and
An information output program which causes an information processing terminal to execute a step of superimposing a plurality of complex signals generated by the step and generating a complex signal simulating a non-frequency selective multipath fading environment. A waveform simulating an elementary wave subjected to Doppler shift, and generating a plurality of complex signals having frequencies orthogonal to each other;
Replacing a plurality of complex signals generated by the step with each other in a predetermined time unit to generate a plurality of complex signals having orthogonality and having no spectral bias; and
Multiplying a plurality of complex signals generated by the step by orthogonal codes;
An information output program which causes an information processing terminal to execute a step of superimposing a plurality of complex signals generated by the step and generating a complex signal simulating a non-frequency selective multipath fading environment.

Images