JP2007096815A - Method for generating code sequence, radio communication apparatus, and radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate the frequency hopping sequence of high secrecy with less interference in a radio communication system utilizing a frequency hopping system based on a spread spectrum communication system. <P>SOLUTION: In the radio communication system comprising a cell including a plurality of radio communication apparatuses for performing the spread spectrum communication of a frequency hopping system of transmitting and receiving signals by successively switching a plurality of carriers of different frequencies on the basis of the code value of a code sequence, and a control station for controlling the code sequence used in the cell, a method for generating the code sequence of frequency hopping has a first step of generating the plurality of different code sequences, and a second step of generating the code sequence of a new sequence length by connecting the two or more generated code sequences by a combination not to be overlapped within the same cell and between the different cells. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for generating a frequency hopping sequence with low interference and high confidentiality in a wireless communication system using a frequency hopping method based on a spread spectrum communication method.

  A frequency hopping method based on a spread spectrum communication method is known as one of communication methods using a wideband signal wave using a spread code. As such a communication method, for example, in a spread sequence generation method using a combination mode of chaotic dynamical systems in a spread spectrum communication system, a combined sequence generated by a combination of two or more chaotic dynamical systems is used. A spread sequence generation method using chaos in a spread spectrum communication system is known (see Patent Document 1).

  Further, as a method of reducing the influence of interference between adjacent channels, frequency channels are divided into even and odd channels, and in the first half of one cycle, a hopping pattern is assigned within the group of even channels, and in the second half of one cycle, A hopping pattern is assigned within a group of odd channels, and the hopping patterns in the first half of one cycle and the latter half of one cycle are connected to synthesize an extended hopping pattern. The frequency channel is switched and modulated according to the extended hopping pattern. A frequency hopping method for transmitting transmitted data is known (see Patent Document 2).

Furthermore, a code sequence generation method using a Reed-Solomon code is known as a code sequence generation method used in the frequency hopping method (see Non-Patent Document 1).
JP-A-11-266179 JP 2000-101481 A Mitsuo Yokoyama, “Spread Spectrum Communication System”, Science and Technology Publishers, 1988, pp. 437-440

  When a code sequence is generated using the method described in the above-mentioned patent document and communication is performed by frequency hopping, the randomness of the code sequence and interference between adjacent channels become problems.

  For example, when the chaos generation method is used as in the invention described in Patent Document 1, the uniform randomness required for the frequency hopping sequence may be lacking.

  In addition, as in the invention described in Patent Document 2 described above, when the channels are divided into even-numbered and odd-numbered channels, interference between adjacent channels is efficiently reduced only when the number of cells is two, but more than that. The number of cells is not effective.

  Also, uniform randomness is ensured by generating a plurality of frequency hopping sequences based on the generator polynomial using the Reed-Solomon code described in Non-Patent Document 1 described above. However, when the Reed-Solomon code is used, the collision probability between hopping frequencies may greatly increase when a cell of a wireless communication system using the Reed-Solomon code operates asynchronously.

  This example will be specifically described.

  In the generation method using the Reed-Solomon code, when cells in the wireless communication system operate asynchronously, code sequences generated separately may collide with each other completely.

  FIG. 13 is an explanatory diagram illustrating an example of occurrence of a collision when different cells operate asynchronously in a conventional wireless communication system.

  In the example of FIG. 13, the number of series Q is set to 17, an a is set to an appropriate value 3 corresponding to the number of series Q, and B is set to 0. In this polynomial, the first sequence “fh1, 0” sets A to 1, and the second sequence “fh2, 0” sets A to 2.

  Further, this wireless communication system associates the generated sequence values with the frequency channels of the respective cells. That is, the generated sequence value becomes the frequency channel number.

  In this wireless communication system, when there is time synchronization between cells, there is no matching value between the two sequences, so there is no frequency channel collision. However, when the cells are asynchronous, the sequence value of the sequence “fh1, 0” and the “sequence fh2, 0” are generated at different timings. In particular, when the sequence value of the sequence “fh1, 0” is delayed by two, it completely coincides with the sequence value of the sequence “fh2, 0”. Therefore, channel collision occurs between cells.

  In addition, the generation method using the Reed-Solomon code has a cycle of the sequence value of Q−1, and thus the cycle is shortened when the number of sequences Q is small. Therefore, there is a drawback that the secrecy is lowered.

  The present invention has been made in view of such problems. In a wireless communication system having a large number of cells, the present invention ensures uniform randomness of a code sequence and reduces interference between adjacent channels. It aims to provide a way to mitigate.

  According to an embodiment of the present invention, a cell including a plurality of radio communication devices that perform spread spectrum communication of a frequency hopping method for sequentially transmitting and receiving a signal by switching a plurality of carriers having different frequencies based on a code value of a code sequence; In a wireless communication system comprising a control station that controls a code sequence used in a cell, the frequency hopping code sequence generation method includes: a first step of generating a plurality of different code sequences; and the generation And a second step of generating a code sequence having a new sequence length by connecting two or more of these code sequences in combinations that do not overlap in the same cell and between different cells.

  According to the present invention, in a wireless communication system, even when each cell operates asynchronously, the collision probability of frequency channels can be kept low. Then, by connecting the generated code sequence, the code sequence can be lengthened and interference between adjacent channels can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1A is a configuration block diagram of a radio communication system using a frequency hopping sequence generation method according to an embodiment of the present invention.

  In the wireless communication system of the present embodiment, the cell 1 and the cell 2 are connected to the control station 30 via a communication path.

  The cell 1 is composed of one master station 21 and a plurality of slave stations 11A, 11B, and 11C. The master station 21 is a wireless communication device that performs wireless communication with the slave stations 11A, 11B, and 11C by frequency hopping. In this cell 1, the hopping frequency by the same code sequence is used, and the master station 21 and the slave stations 11A, 11B, and 11C use different frequencies by time division.

  Note that, similarly to the cell 1, the cell 2 includes one master station 22 and a plurality of slave stations 12A, 12B, and 12C. These configurations are the same as those of the cell 1.

  The control station 30 sets a predetermined unique identifier (ID) for each of the cell 1 and the cell 2. Then, a code sequence based on the set ID is set.

  Although two cells are shown in FIG. 1, the present invention is not limited to this, and a wireless communication system using more cells may be used.

  FIG. 1B is a configuration block diagram of the radio unit 100 provided in the master station 21 and the slave station 11 according to the embodiment of this invention.

  The wireless unit 100 controls wireless communication between the master station 21 and the slave station 11.

  Data for transmission is input to the low-pass filter 101 as a baseband signal from a control unit (not shown). The low-pass filter 101 removes the high-frequency component of the baseband signal, and the primary modulator that is input to the primary modulator 102 converts the input signal into a high-frequency signal and inputs the high-frequency signal to the frequency converter 103.

  On the other hand, an FH (Frequency Hopping) sequence generator 300 generates a code sequence for frequency hopping and inputs the code sequence to the frequency synthesizer 400. The frequency synthesizer 400 converts this code sequence into a hopping synchronized transmission frequency and inputs it to the frequency converter 103.

  The frequency converter 103 converts the high frequency signal input from the primary modulator into a transmission signal based on the transmission frequency input from the frequency synthesizer. The generated transmission signal is transmitted by the antenna 600 via the switch 500. Transmitted as radio waves.

  Further, the received signal received by the antenna 600 is input to the frequency converter 203 via the switch 500. The frequency converter 203 converts the reception signal input via the switch 500 into a high frequency signal based on the transmission frequency input from the frequency synthesizer. The converted high frequency signal is input to the band pass filter 202. The band-pass filter 202 removes a predetermined frequency component from the input high frequency signal and inputs it to the primary demodulator 201. The primary modulator 201 converts the input signal into a baseband signal and inputs it to the control unit.

  Next, a code sequence generated by the FH sequence generator 300 will be described.

  The FH sequence generator 300 determines the order of the transmission frequency corresponding to each channel, which is generated by the frequency synthesizer 400 which is the secondary modulation / demodulation.

  In the wireless communication system according to the embodiment of the present invention, a code sequence is generated using the Reed-Solomon code (see Formula 1) described in Non-Patent Document 1 described above.

  A generation polynomial of a code sequence by this Reed-Solomon code is expressed by a linear expression shown in Equation 1.

  Here, P (i) is the i-th series value, a is an appropriate fixed value called a primitive element, A is a primary coefficient value for the variable ai, B is a constant value, Q is the number of series values, Also called a number. Also, mod. Q means a remainder calculation, that is, a remainder obtained by dividing the whole expression by Q. The generator polynomial is not necessarily limited to a linear expression.

  Note that in a code sequence using a Reed-Solomon code, when a cell of a wireless communication system that uses the code sequence operates asynchronously, the collision probability between hopping frequencies may greatly increase. Therefore, in the embodiment of the present invention, in order to reduce the collision probability even when the cells operate asynchronously, the constant term B for generating the sequence is set to a different value.

  An example of this case will be described below.

  First, in the first series “fh1, 0”, the primary coefficient value A is set to 1 and the constant B is set to 0. The other series “fh1, 1” sets the primary coefficient value A to 1 and the constant B to 1. In this case, each series takes the values shown in FIG.

  In this case, the cells using each series operate asynchronously, and even if a phase shift occurs, the series may not completely match.

  Since B can take Q values (17 in this example from 0 to 16), 17 sequences can be created. A may be set to any value from 1 to Q-1.

  Next, the operation of the FH sequence generator 300 will be described.

  FIG. 3 is a flowchart of processing of the FH sequence generator 300 according to the embodiment of this invention.

  First, FH sequence generator 300 sets parameters for generating a code sequence. The parameters are an order Q equal to the desired hopping number, an arbitrary coefficient A, an appropriate primitive element a corresponding to Q, and a constant C (step S301). Then, the value of B is initialized by setting B to 0 (step S302).

  Next, the FH sequence generator 300 determines whether or not the value of B is smaller than the value of Q (step S303). If the value of B is smaller than the value of Q, the following steps S304 to S308 are repeated.

First, FH sequence generator 300 initializes i by setting variable i for repetition to 0 (step S304). Next, it is determined whether or not the value of the variable i is smaller than the value of Q-1 (step S305). When the value of i is smaller than the value of Q−1, the process proceeds to step S306, and the series value P _B (i) is calculated by the above-described equation 1.

  Next, the FH sequence generator 300 adds 1 to the variable i and returns to step S305. And the process of step S306 and S307 is repeated until the value of i exceeds the value of Q-1.

  Thereafter, if it is determined in step S305 that the value of i is equal to or greater than the value of Q-1, the process proceeds to step S307, and the FH sequence generator 300 adds a new order B obtained by adding a constant C to the value of B. Calculate and return to step S303. The value of C is an integer value in the range of 1 to Q-1.

  After that, if it is determined in step S303 that the value of B is equal to or greater than the value of Q, the FH sequence generator 300 ends the sequence value generation process.

  As a result, a Q sequence consisting of Q-1 sequence values is generated.

  Next, a process for increasing the period using the generated code sequence will be described.

  The FH sequence setting device 300 generates Q code sequences according to the flowchart of FIG. 3 described above. Here, in order to improve the confidentiality of communication, consider the case where the code sequence is made longer.

  In order to make the code sequence longer, the sequence value may be increased. In order to increase the series value, it is necessary to increase the order Q value. However, when the value of the order Q is increased, the calculation formulas for calculating the series value become enormous. Therefore, by using the generated code sequence, different code sequences for each cell are connected without overlapping, thereby generating a new code sequence (extended code sequence) that has been prolonged.

  FIG. 4 is an explanatory diagram of an example of code sequence connection according to the embodiment of this invention.

  The example of FIG. 4 is an example of lengthening the period in a wireless communication system having 5 cells.

  The FH code generator 300 first applies the sequence 1 in the cell 1, and when the sequence 1 is completed, connects the sequence 6 and then connects the sequence 11.

  As a result, the sequence value applied to the cell 1 is expanded to a sequence value having a period three times that of the generated code sequence. Similarly, cell 2 connects series 2, series 7 and series 12. Similarly, the cells 3 to 5 are connected to a series that does not overlap with other cells.

  FIG. 5 is a flowchart of the long period processing of the FH sequence generator 300 according to the embodiment of this invention.

The FH sequence generator 300 sets parameters for the long period processing. The parameters are the number of cells N _C included in the wireless communication system and the number of connected sequences N _A that determines the number of sequences to be connected for a longer period (step S501).

Next, the FH sequence generator 300 is initialized by setting 1 to the variable i _C for repetition (step S502). Then, the constant B is set to a value obtained by subtracting 1 from i _C (step S503).

Next, the FH sequence generator 300 determines whether or not the value of i _C is less than or equal to the value of N _C (step S504). The subsequent steps S505 to S511 are repeated until the value of i _C exceeds the value of N _C.

First, the FH sequence generator 300 is initialized by setting 1 to the variable k _A for repetition (step S505). Then, the P _B sequence corresponding to the current value of the constant B is set as the Pi _C sequence (step S506). Note that the FH sequence generator 300 previously creates a P _B sequence with a constant B equal to or greater than the number obtained by multiplying N _C by N _A.

Next, the FH sequence generator 300 determines whether or not the value of the variable k _A is equal to or less than the value of N _A (step S507). Then, the processes in steps S508 to S511 are repeated until the value of the variable k _A exceeds the value of N _A.

First, in step S508, the FH sequence generator 300 sets a value obtained by adding N _C to the constant B. Then, the P _B sequence is connected to the Pi _C sequence (step S510). Thereafter, 1 is added to the variable k _A and the process returns to step S507.

By the processes in steps S508 to S511, a Pi _C sequence in which N _A P _B sequences are connected is generated.

If it is determined in step S507 that the value of the variable k _A exceeds the value of N _A , the process proceeds to step S509. The FH sequence generator 300 sets the value of the variable i _{C to} a value obtained by adding 1, and returns to step S503.

As a result of the processing according to this flowchart, N _C Pi _C sequences to which N _A P _B sequences are connected are generated.

  Next, processing for changing the hopping number will be described.

  When the code length used for each cell is increased, that is, when the number of hoppings is increased, the confidentiality of wireless communication is correspondingly increased. However, in a wireless communication system in which the number of hops can be changed according to the confidentiality of communication, if a corresponding sequence is generated every time the number of hops is changed, the calculation processing amount of the FH sequence generator 300 increases.

  Therefore, a hopping sequence is generated in advance with the maximum number of hoppings defined in the wireless communication system, and is stored in, for example, a lookup table or a memory. Then, the stored sequence is converted into a sequence of a desired hopping number used during communication.

  FIG. 6 is a flowchart of processing for changing the hopping number according to the embodiment of this invention.

  This process is executed as a process before the start of communication in the wireless communication system.

First, the FH sequence generator 300 sets parameters for changing the number of hops (step S601). The parameters are a maximum hopping number _NHmax defined in the wireless communication system and a desired hopping number _NH used during communication. The maximum hopping number N _Hmax is determined by the bandwidth of the wireless communication system.

Next, the FH sequence generator 300 generates a code sequence whose order is N _Hmax (step S602). This process is the same as the flowchart of FIG. The FH sequence generator 300 stores the generated code sequence (N _Hmax ) in a memory or the like provided in the FH sequence generator 300 of the master station 21 or the slave station 11. The code sequence (N _Hmax ) may be generated by another device. Further, the memory may have any configuration as long as it is a device capable of storing information provided in the master station 21 or the slave station 11.

Next, at the start of wireless communication, a code sequence (N _H ) by N which is a desired hopping number is generated from the generated code sequence (N _Hmax ). Specifically, a remainder calculation is performed on each sequence value of the generated code sequence (N _Hmax ) using N _H. As a result, a code sequence whose sequence value is equal to or less than _NH is generated.

  As described above, if a code sequence having the maximum number of hoppings defined in the wireless communication system is created in advance, an operation with a large amount of processing for generating a code sequence every time communication is started (Formula 1) Without performing the above, it is possible to generate a desired code sequence with only a relatively small remainder calculation.

Instead of the remainder calculation, a sequence excluding values exceeding the desired hopping number may be generated from the code sequence (N _Hmax ) generated by the maximum hopping number. Specifically, when the number of sequence values based on the maximum hopping number is 100 and the desired hopping number is 10, a code sequence in which only the lower 10 sequence values of the sequence value 100 are acquired is generated, The top 90 series values are excluded.

  By doing so, it is possible to reduce the calculation amount in generating the series value.

  Next, the effect by the numerical simulation of the embodiment of the present invention will be described.

First, the calculation of the collision probability between the two sequences p _x (i) and p _y (i) will be described.

  The collision probability of the two sequences is calculated by the following formulas 2 and 3. Formula 2 is an arithmetic expression indicating the coincidence of the sequence values between the channels, and Formula 3 is an arithmetic expression indicating the adjacency of the sequence values between the channels.

  In Equations 2 and 3, x and y are constants B used for generating a sequence, and i is a power, that is, a value corresponding to the order in the sequence.

  Further, from Equation 2 and Equation 3, the number of “matches” and “adjacent” between the two sequences is counted according to the following Equation 4, and the match probability and adjacency probability normalized by the number of sequence combinations and the sequence length: Is calculated.

Note that P _ij (k) is the sequence i-th and j-th collision count, k is a discrete value of phase shift assuming asynchrony, and N _C is the number of cells. _NC C ₂ is the number of combinations for extracting two of N _C pieces.

  FIG. 7 is an explanatory diagram of an example of a simulation result comparing collision probabilities when the remainder calculation is performed according to the flowchart of FIG. 6 described above and when the remainder calculation is not performed. In this example, the simulation conditions are the results of a simulation where the number of cells is 3 and the number of series connections is 6 in the case of hopping numbers 19, 101, and 601, respectively.

  In FIG. 7, when there is no re-residue, that is, when the remainder calculation is not performed, the matching probability is indicated by a circle and the adjacent probability is indicated by a square. These are simulation results calculated using the above-described equations 1 to 4 using a sequence generated with the hopping numbers 19, 101, and 601 as orders.

  On the other hand, when there is a remainder, that is, when remainder calculation is performed, the matching probability is indicated by a dotted line, and the adjacent probability is indicated by a one-dot chain line. These are the simulation results calculated using the series generated by calculating the remainder corresponding to each hopping number using the series generated with the maximum hopping number 1201 as the order.

  As shown in FIG. 7, the collision probability when the remainder calculation is performed is the same as that when the remainder calculation is not performed in both the matching probability and the adjacent probability. That is, although the sequence generated by the remainder calculation from the code sequence generated by the maximum hopping number can be generated with a small amount of computation, the collision probability does not deteriorate.

  Next, a modified example of the above-described code sequence arithmetic expression will be described.

  When the code sequence is generated by the above-described equation 1, i corresponding to the hopping number is an index of a. Therefore, when the hopping number is on the order of several hundreds or thousands, the power of general computers is a power. Operation overflows. Therefore, the code sequence cannot be calculated. Therefore, in the embodiment of the present invention, the above-described formula 1 is transformed into a recurrence formula by a process as shown in the following formula 5.

  By using the recurrence formula shown in Formula 5, power calculation is not necessary. In this case, as an initial value, p (0) with a = 0 is calculated by Equation 6.

  Thereafter, by incrementing the value of i one by one, p (i) is calculated sequentially, and the series value is obtained recursively.

  FIG. 8 is a block diagram showing a configuration in which Equations 5 and 6 are realized by a logic circuit.

  By mounting this logic circuit on the FH sequence generator 300 by software or hardware, it is possible to calculate a code sequence without overflow even when the number of hoppings increases.

  First, an initial value P (0) is input first. The initial value P (0) is subtracted by B by the adder 301, multiplied by a by the multiplier 302, and further added by B by the adder 303. The remainder is calculated by. This calculation result is P (1).

  Next, by inputting the calculated P (1) to the adder 301, the calculation is repeated to obtain P (2). Hereinafter, by recursively calculating this value, the P (i) sequence is obtained. Created.

  Next, reduction of inter-channel interference will be described.

  In order to reduce the interference of sequence values between adjacent channels, it is necessary to reduce the adjacent value collision probability between different code sequences. For this purpose, it is effective to change the constant term B of different code sequences by two or more in the process of the flowchart of FIG. 3 described above. That is, in FIG. 3, different series are created with the constant C set to C> = 2.

  FIG. 9 is an explanatory diagram of an example of a simulation result when the constant C is set to 1 and when the constant C is set to 2 in FIG.

  FIG. 9A shows a sequence generated when the number of hopping 601, the number of cells 3 (that is, the number of sequences 3), the number of sequence connections 3, A = 1, and C = 1. This is a result of generating two sequences shifted up to five each and calculating the collision probability.

  FIG. 9B shows a sequence generated when the number of hopping 601, the number of cells 3 (that is, the number of sequences 3), the number of sequence connections 3, A = 1, and C = 2. This is a result of generating two sequences shifted to 5 one by one and calculating the collision probability.

  As shown in FIG. 9, the matching probability between channels is not much different between FIG. 9 (a) and FIG. 9 (b). That is, the influence of the phase shift is small regardless of the value of B. However, the adjacent probability between the channels is about 0.3 in FIG. 9A, whereas it is about 0.003 in FIG. 9B.

  Therefore, by setting the value of C to 2 or more, the adjacent probability can be greatly reduced. This is because, when the value of C is set to 1, sequences with different sequence values by 1 are generated between different channels. On the other hand, if the value of C is set to 2, sequences with different sequence values by 2 or more are generated between different channels. Therefore, it is possible to generate a code sequence having a lower adjacent probability between channels when the value of C is set to 2. Even when the value of C is 3 or more, the sequence value is shifted by 3 or more and the adjacent probability is lowered, but the number of sequence values is reduced accordingly.

  Next, a method for assigning the generated code sequence to each cell will be described.

  As described above, the code value matching or adjacent interference between channels is reduced depending on how the code sequence is generated.

  In a wireless communication system using frequency hopping, a set code sequence value is assigned to a corresponding frequency channel of each cell. At this time, in order to further reduce the coincidence collision and the interference between adjacent channels, a sequence value is assigned to each channel as follows.

  FIG. 10 is an explanatory diagram of code values assigned to each cell according to the embodiment of this invention.

  In the example shown in FIG. 10, three cells are configured in the wireless communication system, the frequency channel is set to 24 channels, the code value is set to 1 to 4, that is, the hopping number is set to 4. The control station 30 executes the assignment of the sequence value to each cell.

  First, the control station 30 assigns the code value 1 to the channel 1 in the cell 1, assigns it to the channel 3 separated from the channel assigned to the cell 1 in the cell 2, and assigns the code value 1 to the cell 2 in the cell 3. Is assigned to channel 5 which is one more apart.

  By assigning code values in this way, even when each cell has the same code value 1, since each cell uses a different frequency channel separated by one, code value matching between channels is avoided and adjacent There is no influence of inter-channel interference.

  Next, sequence value allocation using time division between cells will be described.

  Here, a time division wireless communication system using the same code sequence in the same cell is considered. In this case, the search time of the hopping frequency can be saved by setting the code sequence to be used and the position in the code sequence, that is, the hopping frequency, to coincide on the transmission side and the reception side. Therefore, high-speed synchronization acquisition is possible.

  Here, the code sequence value is set using two pieces of information, that is, identifier (ID) information uniquely set for each cell and time information.

FIG. 11 is an explanatory diagram of an example of allocation of ID information and time information according to the embodiment of this invention. In the wireless communication system, ID information uniquely set for each cell is set. As for this ID information, the same ID number is set in advance for the wireless communication devices (master station and slave station) included in the same cell. Further, the wireless communication devices in the same cell have time information synchronized when the wireless communication system is started up. Each wireless communication device may acquire time information from time to time by GPS (Global Positioning System) and synchronize the time information.

  Then, in each wireless communication device, a sequence value to be used is determined based on the ID information and time information, and transmission / reception processing is performed using a hopping frequency corresponding to the sequence value.

  Note that the ID information can be appropriately changed like a password. The time information uses a relative time with respect to the current time with the system startup time set to zero. Alternatively, an arbitrary time may be set as a password when the system is started up.

  In the example of FIG. 11, the wireless communication device belonging to the cell 2 corresponds to the code sequence ID2, and the code sequence ID2 uses the code sequence of ch7 of the ID2 sequence when the time is T7. Performs communication by frequency hopping. If a slight error occurs in the set time, the frequency hopping can be synchronized by executing a synchronization acquisition process in each wireless communication device.

  FIG. 12 shows an example of a processing procedure according to the embodiment of the present invention.

  First, the control station 30 sets ID information that is a unique identifier for each cell and the current time and time (step S1201).

  Next, the control station 30 acquires ID information of the cell regarding an arbitrary cell in the wireless communication system, and determines a code sequence corresponding to the acquired ID information (step S1202).

  Next, the control station 30 acquires time information and determines a code position in the code sequence corresponding to the acquired time information (step S1203).

  And the control station 30 produces | generates the code value applied to the said cell from the code sequence determined by step S1202 and S1203, and the code position in it (step S1204).

  Then, the control station 30 determines the frequency channel corresponding to the cell ID information and the time information from the correspondence table as shown in FIG. 11 (S1205). The determined frequency channel is notified from the control station 30 to each slave station 11 or 12 via the master station 21 or 22.

  Through the above processing, the code sequence used by the cell is determined from the ID information and the time information.

  Next, another example of generating a code sequence will be described.

As described above, the Reed-Solomon code is used to generate the code sequence. On the other hand, it is also possible to use code sequences calculated by other options. Examples of code sequences using OCC (One-Coincidence Code) codes will be described below. The OCC code is written by Mitsuo Yokoyama, “Spread Spectrum Communication System”, Science and Technology Publishers, 1988, pp. 437-440.

  A code sequence based on the OCC code is calculated by the following Expression 7.

  Equation 7 is a code sequence generated by an OCC code based on the prime number 7. The number of sequence values, the sequence length, and the number of sequences are all 6.

  The OCC code has an advantage that a code sequence having a low collision probability is generated even in an asynchronous operation. However, as compared with the code sequence generated by the processing of the flowchart of FIG. 3 using the Reed-Solomon code as described above, the code sequence generated by the OCC code has one less number of sequences.

As described with reference to FIGS. 4 and 5, a plurality of sequences can be connected in order to create a long-period sequence from the generated OCC code sequence. For example, fh _OCC1 and fh _OCC4 , fh _OCC2 and fh _OCC5 , and fh _OCC3 and fh _OCC6 are connected. As a result, three code sequences having a period twice as long as the original code sequence are obtained as shown in Equation 8 below.

  Similarly, the number of hops can be changed from the generated OCC code sequence by applying the process shown in FIG. Similarly, code sequence assignment as described in FIGS. 10 and 11 can also be applied.

  As described above, in the radio communication system according to the embodiment of the present invention, the code sequence used for frequency hopping is generated with a sequence having different constant terms of the polynomial of the Reed-Solomon code, so that collision between adjacent channels can be reduced. it can. Then, by connecting the generated code sequences in a predetermined combination and lengthening the code values of the code sequences, it is possible to improve confidentiality and reduce frequency channel coincidence collisions. . Further, when assigning code sequences to each cell in the system, code values are assigned with one or more frequency channel intervals, so that matching and adjacency in frequency channels can be reduced. Furthermore, when assigning a code sequence to each cell in the system, by switching the frequency channel of the code sequence to be applied according to the ID information and time information for each cell, it is possible to further reduce matching and adjacency in the frequency channel. it can. Furthermore, the generation of the code sequence is not limited to the Reed-Solomon code, and various code systems such as an OCC code can be used.

  The present invention is applicable to all wireless communication systems to which a frequency hopping method is applied. As a system using the frequency hopping method, for example, it can be applied to Bluetooth, wireless LAN (IEEE802.11), and the like. In particular, the effect of the present invention is high in a system with a very small number of hops and a system with a variable number of hops.

1 is a configuration block diagram of a wireless communication system using a frequency hopping sequence generation method according to an embodiment of the present invention. It is a block diagram of the configuration of a radio unit provided in a master station and a slave station according to an embodiment of the present invention. It is explanatory drawing of an example of a code sequence when the constant B of a generator polynomial is changed. It is a flowchart of a process of the FH series generator of embodiment of this invention. It is explanatory drawing of an example of the connection of the code series of embodiment of this invention. It is a flowchart of the process of lengthening of the FH series generator of embodiment of this invention. It is a flowchart of the process of hopping number change of embodiment of this invention. It is explanatory drawing of an example of the simulation result which compared the collision probability of embodiment of this invention. FIG. 3 is a configuration block diagram realized by the logic circuit according to the embodiment of the present invention. It is explanatory drawing of an example of the simulation result when the constant C of embodiment of this invention is set to 1, and the constant C is set to 2. It is explanatory drawing of the code value allocated to each cell of embodiment of this invention. It is explanatory drawing of an example of allocation of ID information and time information of embodiment of this invention It is a flowchart of an example of the processing procedure of the channel allocation of embodiment of this invention. It is explanatory drawing which shows the example of collision occurrence of the conventional radio | wireless communications system.

Explanation of symbols

1, 2 cell 11A, 11B, 11C, 12A, 12B, 12C slave station 21, 22 master station 30 control station 100 radio unit 300 FH sequence generator

Claims (11)

A wireless communication device that performs spread spectrum communication of a frequency hopping method in which a plurality of carriers having different frequencies are sequentially switched based on a code value of a code sequence to transmit and receive signals, a cell including a plurality of the wireless communication devices, and the cell A method for generating the frequency hopping code sequence in a wireless communication system comprising:
A first step of generating a plurality of different code sequences;
A code sequence generation method comprising: a second step of generating a code sequence of a new length by connecting two or more of the generated code sequences by a combination that does not overlap.   The said 1st step produces | generates a several different code sequence by setting the constant term of the polynomial by the Reed-Solomon code used in order to produce | generate the said code sequence to a different value. A method for generating the described code sequence.   The first step generates a plurality of different code sequences by setting a constant term of a polynomial by a Reed-Solomon code used for generating the code sequence to a value different by at least two or more. Item 2. The code sequence generation method according to Item 1. The first step includes
A plurality of different code sequences are generated in advance according to the maximum code sequence length in the cell, and the generated code sequences are stored,
The remainder of the stored code sequence is calculated by a predetermined value to generate a code sequence having a new sequence length, or a code value exceeding a predetermined length is deleted from the stored code sequence, The code sequence generation method according to claim 1, wherein a code sequence having a new length is generated.   The first step calculates a first code value of a code sequence as an initial value in a polynomial using a Reed-Solomon code, and substitutes the calculated initial value into the polynomial for second and subsequent times. The code sequence generation method according to claim 1, wherein the code sequence is generated by calculating a code value.   A step of setting a code sequence of a radio communication apparatus in a cell by allocating one sequence value to different frequency channels with an interval of one or more frequency channels for each cell is provided. Item 2. The code sequence generation method according to Item 1. Setting a unique identifier for the cell, and setting a correspondence between the identifier and a code sequence per unit time;
The code sequence generation method according to claim 1, further comprising: setting a code sequence of a wireless communication device in the cell based on the correspondence relationship. In a wireless communication device that performs spread spectrum communication of a frequency hopping method in which a plurality of carriers having different frequencies are sequentially switched based on a code value of a code sequence to transmit and receive signals,
A code sequence generation unit for generating the code sequence;
The code sequence generator is
A plurality of different code sequences are generated in advance according to the maximum code sequence length in the cell, and the generated code sequences are stored,
The remainder of the stored code sequence is calculated by a predetermined value to generate a code sequence having a new sequence length, or a code value exceeding a predetermined sequence length is deleted from the stored code sequence, A radio communication apparatus that generates a code sequence having a new sequence length.   The code sequence generation unit calculates a first code value of a code sequence as an initial value in a polynomial using a Reed-Solomon code, and substitutes the calculated initial value into the polynomial for the second and subsequent codes. The wireless communication apparatus according to claim 8, wherein the code sequence is generated by calculating a code value. A wireless communication device that performs spread spectrum communication of a frequency hopping method in which a plurality of carriers having different frequencies are sequentially switched based on a code value of a code sequence to transmit and receive signals, a cell including a plurality of the wireless communication devices, and the cell In a wireless communication system comprising a control station that controls a code sequence used,
The control station
A radio communication system, wherein a code sequence of a radio communication device in a cell is set by assigning one sequence value to different frequency channels at intervals of one or more frequency channels for each cell. The control station
Set a unique identifier for the cell, set the correspondence between the identifier and a code sequence per unit time,
The wireless communication system according to claim 10, wherein a code sequence of the wireless communication device in the cell is set based on the correspondence relationship.

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