JP2005045663A - Spread spectrum communication method and equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the hardware scale of a transmitter and a receiver small and also downsize the circuit for generating a hopping pattern in a frequency hopping communication system. <P>SOLUTION: In a transmitting side, frequency hopping patterns are generated as the combination of a plurality of patterns. In a receiving side, the frequency hopping patterns are separated for every group and demodulated step by step. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to frequency spread spectrum communications. The present invention relates to spread spectrum communication for selecting a frequency hopping pattern based on transmission information. The present invention is useful as an improvement of FH / Multilevel FSK (Frequency Hopping by Multilevel Frequency Shift Keying) method. However, the present invention is not limited to this, and the principle of the present invention can be widely applied to any frequency hopping communication.

JP 2000-91957 (Applicant, Soka University) JP 2003-124848 A (Applicant, Tamaty L.O.) D.J.Goodman etal "Frequency-hopped multilevel FSK for mobile radio" Bell System Technical Journal 59-7 pp1257-1275 (Sept. 1980) Marubayashi et al. "Spread spectrum communication and its applications" published by IEICE, May 1998

5 and 6 are block configuration diagrams for explaining the FH / Multilevel FSK system. This method is described in [Non-Patent Document 1] (Goodman). FIG. 5 is a block diagram of the transmission apparatus. The input data is converted by the encoder 1 into code words consisting of 2 ^k levels divided every k bits. The address pattern generator 2 generates a hopping pattern specific to the system as an L-chip address code consisting of 2 ^k levels. When the input data k-bit length is T and the one-chip length of the address is τ, the relationship is T = τL.

The encoder 1 selects one of the 2 ^k levels corresponding to the state of the input data k bits and outputs it L times. The output of the encoder 1 and the address code are added by a mod (2 ^k ) adder 3, and a tone having a frequency corresponding to the added output is generated from the tone generator 4, which becomes a modulation output. This modulation output becomes a modulation input of a frequency modulator (not shown), and a frequency hopping signal is transmitted from the frequency modulator. This is an intermediate frequency signal, and this intermediate frequency signal is converted into a high frequency signal of a predetermined frequency band and transmitted to the space.

FIG. 6 is a configuration diagram of a receiving apparatus corresponding to this. This reception input is an intermediate frequency signal obtained by frequency-converting a high frequency signal. This is converted from a frequency signal to a level signal by the spectrum analyzer 5. The receiving apparatus includes an address pattern generator 6 that generates an address pattern equal to that of the transmitting apparatus, and the generated address code is supplied to a mod (2 ^k ) subtractor 7. The mod (2 ^k ) subtracter 7 performs subtraction of an address code from the converted input level. The signal of the other system is mixed as noise in the reception input, but at the output of the mod (2 ^k ) subtracter 7, the signal of the system is aligned at the same level, but the noise is dispersed in many levels. The decision decoder 8 restores the data by determining the level having the most components as the correct level by majority decision.

This situation will be described with reference to FIGS. 7 and 8. FIG. 7A shows transmission codewords, the horizontal axis represents time, and the vertical axis represents level. The frequency is set from 1 to 2 ^k . FIG. 4B shows a transmission address pattern. Similarly, the horizontal axis represents time, and the vertical axis represents level. This address pattern is set as a system-specific pattern from level 1 to level L. FIG. 7 (c) represents the transmission spectrum, and the horizontal axis represents time, but the vertical axis represents frequency. When the transmission codeword shown in FIG. 7A is mod (2 ^k ) added to the address code shown in FIG. 7B and converted into a frequency tone, a transmission spectrum as shown in FIG. 7C is obtained. It becomes.

When this transmission spectrum is received by the receiving apparatus, as shown in FIG. 8 (a), not only the X mark representing a signal but also the level information marked with a circle representing noise is received at each timing. In FIG. 8A, the horizontal axis represents time, and the vertical axis represents frequency. FIG. 8B shows an address pattern of the receiving device. This address pattern is set equal to the address pattern of the transmitting device. When mod (2 ^k ) is subtracted using this address pattern, a level signal as shown in FIG. 8C is obtained. That is, the signal x of the system appears at the same level, but the signal or noise of the other system is distributed to a number of levels as a result of the mod (2 ^k ) subtraction, and this is identified and decoded by the majority decision. be able to.

  This prior art (FH / Multilevel FSK system) is described in detail in the above [Non-Patent Document 2], especially pages 37-49.

  The inventor of the present application disclosed an invention for improving the frequency utilization efficiency for this communication method in the above-mentioned [Patent Document 1]. This is hereinafter referred to as “prior invention”. In this method, the selection of the frequency hopping pattern is not assigned to an address, but is assigned to information transmission, so that the amount of information that can be transmitted is expanded two-dimensionally.

  Furthermore, the inventor of the present application has disclosed the invention described in [Patent Document 2] as a method for improving the frequency utilization efficiency. This is a tone generator provided in the transmission apparatus so as to correspond to a combination of i tones out of m tones with respect to an n-level input signal.

  The above prior art has a low error rate with respect to noise from other systems, and the frequency utilization efficiency is much better than other frequency hopping communication systems. This method is expected to be able to effectively use radio resources and reduce transmission power in the future.

  However, in the frequency hopping / spread spectrum communication method that uses a plurality of hopping patterns for information transmission to improve the information communication speed, the information communication speed can be increased by increasing the number of hopping patterns that can be used. When the number of hopping patterns is increased, there is a disadvantage that the hardware scale of the transmission / reception apparatus increases. That is, the number of patterns that can be used is naturally limited from the viewpoint of the circuit scale that can be installed in the communication device.

  Considering the case where N hopping patterns are used (for example, 256), it is necessary to provide a circuit for generating N hopping patterns in each of the transmission device and the reception device and operate them simultaneously. is there. In other words, N hopping pattern generating circuits that can operate simultaneously must be prepared in parallel in the transmitter and the receiver as hardware. In particular, the hardware of the receiving apparatus further requires N subtracting circuits operating in parallel. Therefore, the circuit scale of the receiving device increases. As the number of hardware operating in parallel at the same time increases, the instantaneous power required to operate the device also increases.

  The present invention is to improve this, and to provide a communication method by frequency hopping / spread spectrum, a transmitting apparatus, and a receiving apparatus which can greatly reduce the number of hopping patterns and the number of subtracting circuits to be prepared. Objective. An object of the present invention is to further improve the above-mentioned prior invention by taking advantage of the use of frequency hopping pattern selection for information transmission instead of assigning frequency hopping patterns as system addresses. An object of the present invention is to provide a communication method, a transmission device, and a reception device that can increase the frequency utilization efficiency of frequency hopping spread spectrum communication and reduce the hardware scale of the communication device. An object of the present invention is to provide a frequency hopping spread spectrum communication method, a transmission device, and a reception device that can reduce the instantaneous power of a power supply device required for the device.

  The present invention is characterized in that a number of hopping patterns are synthesized by a combination of a plurality of hopping pattern groups on the transmission side, and the hopping patterns are separated into groups on the receiving side and demodulated stepwise.

It will be easier to understand by using an example in which the above N (eg, 256) hopping patterns are used. In order to use 256 hopping patterns, it is necessary for the conventional apparatus to provide 256 hopping pattern generation circuits for both the transmitting apparatus and the receiving apparatus. Furthermore, it has been stated that the receiving device requires 256 subtracting circuits. Exemplifying the configuration of the present invention, in order to generate 256 hopping patterns in the transmission apparatus, two patterns of 16 patterns are combined, that is, 16 × 16 = 256 (pieces).
Generate a hopping pattern. With this configuration, the number of hopping pattern generation circuits prepared in the transmission device is 16 + 16 = 32 (pieces)
It will be good. The same applies to the receiving apparatus, and the number of hopping pattern generation circuits required for 256 is 32. Further, in the receiving apparatus, 32 subtraction circuits are required for each hopping pattern generation circuit, so that the scale of the apparatus hardware is greatly reduced.

  In this example, since the number of hopping pattern generation circuits (and subtraction circuits) has been reduced from 256 to 32, the reduction effect is 1/8, but the number m of hopping patterns is further large. Considering the case, the circuit scale is reduced to 1/16, 1/32, 1/64, and so on.

  That is, according to the present invention, the scale of the hardware circuit mounted on the transmission device and the reception device can be drastically reduced. As a result, the size of the apparatus can be reduced, and the price of the apparatus hardware can be drastically reduced.

In other words, the first aspect of the present invention is an invention of a communication method in which K information (K = 2 ⁿ ) represented by n bits of input data is converted into K ₁ level information (K ₁ = 2 ^k ) from the transmission side. And K ₂ hopping pattern combination information (K ₂ = 2 ^{m + 1} , where K = K ₁ + K ₂ ), in the spread spectrum communication method, a large number of hopping patterns are combined by combining a plurality of hopping pattern groups on the transmission side Is synthesized.

  Furthermore, the present invention is characterized in that, on the receiving side of the signal transmitted by the communication method, the hopping pattern is separated for each group and demodulated stepwise.

With the receiving side detects the reception signal level, the _two K corresponding to the hopping pattern ^{_{(K 2 = 2 m + 1}} ) the hopping pattern occurred, and a first input the detection output of the received level in the common, the hopping K ₂ (K ₂ = 2 ^{m + 1} ) mod (K ₁ ) subtractions, each using the pattern as a second input, are executed, and among the subtraction outputs, a pattern in which a number of the same level appears and its level are used as determination outputs. It may be configured to include a step of restoring n-bit information from a combination of one of the K ₂ patterns as a determination output and one level of K ₁ decoded by the pattern. .

However,
K = K ₁ + K ₂
K ₁ = 2 ^k
K ₂ = 2 ^{m + 1}
It is.

A second aspect of the present invention is an invention of a communication apparatus, wherein K pieces of information (K = 2 ⁿ ) represented by n bits of input data is converted into K ₁ pieces of level information (K ₁ = 2 ^k ) and K ₂ pieces of information. In a spread spectrum communication apparatus including means for transmitting as hopping pattern combination information (K ₂ = 2 ^{m + 1} , K = K ₁ + K ₂ ), means for synthesizing a number of hopping patterns by combining hopping pattern groups It is characterized by.

  The means for synthesizing a large number of hopping patterns by combining the hopping pattern groups is preferably configured such that the synthesizing procedure is set so that the pattern groups can be separated step by step on the receiving side.

  With this configuration, the scale of hardware provided in the transmission device and the reception device can be dramatically reduced. With this configuration, it is possible to reduce the size of the apparatus, and it is possible to implement this communication method for mobile devices such as mobile phones and PDAs (Personal Digital Assistants), and to expand the scope of application. be able to. Reducing the device hardware not only reduces the device price, but also reduces the size of the device hardware, thereby improving the manufacturing yield of the integrated circuit and further reducing the device price. According to the present invention, since the number of hardware operating simultaneously is reduced, the instantaneous power of the power supply device that supplies power to the transceiver device can be designed to be small.

(Example 1)
Embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a block diagram of the main part of a transmitting apparatus according to an embodiment of the present invention. In this apparatus, K-bit input binary data arriving at the input terminal 10 is supplied to the encoder 11. The encoder 11 encodes this input data into a level signal. At this time, the input K bit is divided into two, K ₁ bit of which is given to the level conversion circuit 12, and K ₂ bit is given to the hopping pattern generation circuit 13.
K = K ₁ + K ₂ (bit)
However, K ₁ = 2 ^k , K ₂ = 2 ^{m + 1}
It is.

The level conversion circuit 12 generates a level signal L _h corresponding to the K ₁ bit input. The hopping pattern generation circuit 13 generates C _k hopping patterns corresponding to the K ₂ bit input level signal. The C _k hopping patterns are input to the modulo-n adder 14 together with the level signal L _h , and the output of the adder 14 is supplied to the tone generator 15. The output of the tone generator 15 is supplied from the modulation input terminal 16 as a modulation input of the transmitter.

The feature of the present invention lies in the configuration of the hopping pattern generation circuit 13. That is, K ₂ = 2 ^{m + 1 which} is input to the hopping pattern generation circuit 13
The bit signal is divided into two and supplied to the hopping pattern generation circuit 17 of the hopping pattern group A and the hopping pattern generation circuit 18 of the hopping pattern group B. The two hopping pattern generation circuits 17 and 18 generate hopping patterns, respectively, and the outputs of the outputs A group and B group are supplied to the synthesis circuit 19, and a number of hopping patterns C are combined as a combination of the two hopping pattern groups. Generate _k .

Hopping pattern generating circuit 17 is, for example, K _2/2 pieces of the m hopping pattern A ₁ in response to the input, A _2, ·····, generates A _m (A group). This is group A. Hopping pattern generating circuit 18 is also hopping pattern B ₁ corresponding to the K _2/2 inputs, B _2, ·····, generates a B _m (B group). This is group B. When a hopping pattern A _i and a hopping pattern B _j are selected from the A group and the B group, respectively, and added by the adder 19, a hopping pattern C _k is _obtained .
C _k = A _i + B _j
Here, i and j are 1, 2, 3,..., M, respectively. And k: 1, 2, 3, ... m ²
It becomes. The number of combinations of this hopping pattern is m ² . That is, m ² hopping patterns can be generated from 2m hopping patterns. This means that two hopping pattern generation circuits 17 and 18 that generate m hopping patterns may be used without preparing m ² hopping pattern generation circuits. In this way, the hardware can be significantly reduced.

  FIG. 2 is a block diagram of a receiving apparatus according to an embodiment of the present invention corresponding to the transmitting apparatus. This apparatus includes a detector 21 that detects a received signal level from an intermediate frequency signal arriving at a receiving input terminal 20. Further, this receiving apparatus includes a hopping pattern generator 23 for generating a hopping pattern corresponding to the hopping pattern generating circuit 13 of the transmitting apparatus. In this example, the hopping pattern generation circuit 23 generates m hopping patterns of the group A described for the transmission device. The outputs of the m hopping pattern generation circuits 23 are respectively supplied to m number of subtracters 22, and the subtracters 22 subtract m number of hopping patterns of the A group from the input signals.

The output minus pattern A _l is
L _h + C _k −A ₁ = L _h + B _j + (A _i −A ₁ )
It becomes. Here, the branch where A _i −A _l = 0 is detected by the determination circuit 25 from the output of each subtractor 22. Among the switches 26 provided at the outputs of the determination circuit 25, the switch 26 is closed for the branch where A _i −A _l = 0, and the signal is connected to the next stage. All the switches in the branch where A _i −A _l ≠ 0 are opened, and control is performed so that the output does not flow out to the next stage. The output L _h + B _{j of the} branch where A _i −A _l = 0 passing through the closed switch among the switches 26 is input to the next stage.

In this next stage, m hopping pattern generation circuits 24 for generating the B group hopping patterns are provided. Furthermore, m subtractors 27 for inputting the output L _h + B _j to one terminal thereof from the previous stage are provided. The outputs of the m hopping pattern generation circuits 24 are connected to the other terminals of the m subtractors 27, respectively.

The m subtractors 27 subtract the B group hopping pattern from the input L _h + B _j , respectively. The output obtained by subtracting the hopping pattern B _q is L _h + B _j −B _q
However, the decision circuit 28 detects a branch where B _j −B _q = 0 from among them. Then, the output side switch 29 is closed for the branch, and the output side 29, ie, 29 is opened for the other branches. In this way, L _h can be extracted from the output. In this way, all of A _i , B _j , and L _h can be determined in the receiving apparatus by the two-stage division.

Next, a configuration method of the transmission hopping pattern will be described with reference to FIG. That is, in the above description, A _i −A _l = 0
Or B _i -B _q = 0
An example of a method of configuring a hopping pattern for logically enabling such selection will be described.

FIG. 3A is an explanatory diagram of a hopping pattern on the transmission side, and FIG. 3B is an explanatory diagram of a hopping pattern on the reception side. This figure is an example of the number of levels (vertical) 8 and the number of chips (horizontal) 6. First, as shown in FIG. 3 (a) _Lh , 3 bits of input data are converted into one of eight (= 2 ³ ) levels (in this example, level “6”). The hopping pattern C _k ) is added to this level matrix (L _h ). The hopping pattern matrix is added to the “hopping pattern matrix” in FIG. 3A so that it can be separated stepwise on the receiving side. As shown, the left side 3 chips constitute the A group hopping pattern, and the right side 3 chips constitute the B group hopping pattern. Then, the hopping pattern A _i in the A group and the hopping pattern B _j in the B group are connected to form a 6-chip hopping pattern (C _k ). 1 is added to obtain an output matrix (L _h + C _k ).

On the receiving side, as described with reference to FIG. 2, the output matrix (L _h + C _k ) is demodulated by the detector 21, but the subtracter 22 first subtracts the hopping pattern of the A group. Then
(L _h + C _k ) −A _i
Among them, there are those in which the left three chips are arranged in a horizontal line as shown in the left of FIG. Since the other patterns are random patterns, it can be known which one corresponds to the transmitted pattern. This is the reception first stage division output (L _h + B _j ). This is further subtracted by the subtractor 27 from the B group hopping pattern. This time, there are those with 3 chips on the right side in a row. Other patterns are random patterns that can be selected. In this way, a matrix in which 6 chips are arranged in a horizontal row is obtained. This is the second stage division output (L _h ). In a practical device, noise is superimposed on the line and circuit between the transmission side and the reception side, so it is necessary to determine which line is aligned using a majority decision for those arranged in a horizontal line. It is.

(Example 2)
As described above, the configuration in which chips are divided into groups is easy to understand. However, since the number of chips increases, transmission efficiency decreases. On the other hand, a method of separately demodulating the group step by step on the receiving side by separating and synthesizing the group in the same chip can be considered. Transmission efficiency can be improved by this method. The even-odd classification method shown below is an example based on this concept. An example of 5 chips will be described with reference to FIG.

The level is divided into an even level and an odd level, the even level is represented by E, and the odd level is represented by O. Group A is a pattern in which E and O are mixed for 5 chips. For example, A _i is a pattern called EOEEO, and A _k is a pattern called OEOEE. Then, A _i -A _k becomes OOEEO, and also a pattern in which E and O are mixed. Patterns in which A _i -A _k is EEEEE or OOOOOO must be excluded. That is, the rule is that only one hopping pattern can be selected from the same EO pattern or a pattern obtained by inverting this and EO.

All combinations of E and O for 5 chips are 2 ⁵ = 32
There are, however, complementary combinations are excluded. For example, if you add EOOEO and OEEOE to each other, it becomes OOOOO, so you cannot use both. Then, the number of EO combination patterns that can be used is 16. In general, when the number of chips is L, the number of combination patterns that can be used is 2 ^(L−1) . In other words, E and O may be arranged in the A group in correspondence with 5-digit binary numbers from 0 to 15.

Next, the B group constitutes a hopping pattern with all E or all O. Here, E is EEEEE for all. Then, if the pattern obtained by subtracting A _k from A _i + B _j becomes EEEEE, A _i = A _k
Thus, A _i can be selected. From the rest of the pattern obtained by subtracting the A _i by subtracting the B _h, if you find a B _h the difference becomes zero (or level number 2 ^n), the B _h is B _j.

When a level is added, the level is an EEEEEE or OOOOO pattern. In this case, if the pattern obtained by subtracting A _k first is EEEEE or OOOOOO, it is determined that A _i = A _k .

  In the case of this method, the number of patterns that the A group can take depends not on the number of levels but on the number of chips. Since it is sufficient for the B group to have an even number of levels, it is possible to select a considerably rich pattern.

  According to the present invention, the hardware of the transmission device and the reception device can be reduced in size, so that it can be used for mobile communication devices, mobile phones, and PDAs (Personal Digital Assistants). It can also be used for digital subscriber line (xDSL) communication and power line communication.

1 is a block diagram of a transmitting apparatus according to an embodiment of the present invention. The block block diagram of the receiver of the present invention embodiment. The signal processing explanatory drawing by the apparatus of 1st Example of this invention. The signal processing explanatory drawing by the 2nd Example apparatus of this invention. The transmission apparatus block diagram for demonstrating the principle of this invention apparatus. The block diagram of the receiver for demonstrating the principle of this invention apparatus. The signal processing explanatory drawing in the transmission side for demonstrating the principle of this invention apparatus. The signal processing explanatory drawing in the receiving side for demonstrating the principle of this invention apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Encoder 2 Address pattern generator 3 Adder 4 Tone generator 5 Spectrum analyzer 6 Address pattern generator 7 Subtractor 8 Decision decoder 10 Input terminal 11 Encoder 12 Level conversion circuit 13 Hopping pattern generation circuit 14 Adder ( Modulo n)
Reference Signs List 15 tone generator 16 modulation output (input) terminal 17 hopping pattern generation circuit 18 hopping pattern generation circuit 19 synthesis circuit 20 reception input terminal 21 detector 22 subtractor 23 hopping pattern generation circuit (group A)
24 Hopping pattern generation circuit (Group B)
25 Judgment circuit 26 Switch 27 Subtractor 28 Judgment circuit 29 Switch

Claims (5)

From the transmission side, K information (K = 2 ⁿ ) represented by n bits of input data is transmitted as K ₁ level information and K ₂ hopping pattern combination information (where K = K ₁ + K ₂ ). In the spread spectrum communication method,
A spread spectrum communication method characterized in that a large number of hopping patterns are synthesized by a combination of a plurality of hopping pattern groups on the transmission side.   2. The spread spectrum communication method according to claim 1, wherein the hopping pattern is separated into groups and demodulated step by step on the reception side of the signal transmitted by the communication method according to claim 1. In addition to detecting the received signal level, K ₂ (K ₂ = 2 ^{m + 1} ) hopping patterns corresponding to the hopping pattern are generated, and the detection level detection output is commonly used as a first input. The second input K ₂ (K ₂ = 2 ^{m + 1} ) mod (K ₁ ) subtraction is executed, and among the subtraction outputs, a pattern in which a number of the same level appears and its level are set as the determination output. 3. The spread spectrum communication method according to claim 2, further comprising a step of restoring n-bit information from a combination of one of the K ₂ patterns and one level of K ₁ decoded by the pattern. . The information of K number (K = 2 ⁿ ) represented by n bits of input data is combined with K ₁ level information (K ₁ = 2 ^k ) and K ₂ hopping pattern combination information (K ₂ = 2 ^{m + 1} , where K = Spread spectrum communication apparatus including means for transmitting as K ₁ + K ₂ )
A spread spectrum communication apparatus comprising means for synthesizing a number of hopping patterns by a combination of hopping pattern groups.   5. The spread spectrum communication apparatus according to claim 4, wherein the means for synthesizing a large number of hopping patterns based on the combination of the hopping pattern groups is configured so that the pattern groups can be separated step by step on the receiving side.

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