WO1997035397A1

WO1997035397A1 - Frequency hopping radiocommunication system and synchronous catching method

Info

Publication number: WO1997035397A1
Application number: PCT/JP1996/000679
Authority: WO
Inventors: Yasuo Ogoshi; Ritsuko Sasae; Masahiro Ito
Original assignee: Hitachi, Ltd.
Priority date: 1996-03-15
Filing date: 1996-03-15
Publication date: 1997-09-25

Abstract

A frequency hopping radiocommunication system for transmitting and receiving signals while periodically hopping a carrier wave frequency in accordance with a predetermined hopping sequence, comprises a frequency synthesizer (50) for switching the frequency of the output signal, a detection circuit (32) for detecting a reception signal at the output signal frequency from the frequency synthesizer, a demodulation circuit (35) for demodulating the reception signal from the output of the detection circuit, and a hopping controller (55) for controlling the synthesizer. The hopping controller has a low speed hopping mode (102 to 106) for instructing the frequency synthesizer to switch the frequency for a predetermined cycle in accordance with a hopping frequency sequence which defines a hop sequence for different frequencies, and a high speed hopping mode (121 to 135) for instructing the frequency synthesizer to switch the frequency at a switching rate substantially corresponding to one cycle of the sense frequency sequence during the duration for which each carrier wave frequency continues in accordance with a sense frequency sequence which defines a hop sequence of a limited number of frequencies existing in discrete hop positions in the hopping frequency sequence. When the carrier is detected from the detection circuit output while the frequency synthesizer outputs a specific frequency in the high speed hopping mode, the operation mode is switched to the low speed hopping mode, using the hop position corresponding to a specific frequency in the hopping frequency sequence as the starting point.

Description

Specification

Frequency hobbing wireless communication system and synchronization acquisition method

The present invention relates to a wireless communication system, and more particularly, to a frequency hobbing wireless communication system and a synchronization acquisition method in which a communication device on a transmission side and a communication device on a reception side communicate while hopping a carrier frequency according to a predetermined hobbing sequence. Background technology

The spread spectrum communication method is a communication method in which a transmission signal is spread over a frequency band wider than the spanned bandwidth and transmitted, and is excellent in interference resistance and confidentiality. In the spread spectrum communication system, the spectrum is spread by replacing each symbol (bit) of the transmission signal with a spreading code consisting of a plurality of chips. There is a “frequency hopping method” that spreads the spectrum by periodically hopping the output frequency (carrier frequency) of a local oscillator that converts a signal into a radio frequency band.

In a frequency hopping communication system, the transmitting and detecting frequencies are synchronized with each other and hopped according to the same hopping sequence (hopping pattern) as the transmitting communication device and the receiving communication device. The hopping sequence of the carrier frequency used at this time includes one having a relatively short repetition period and one having a long repetition period in order to improve confidentiality. Regardless of the hopping sequence in any of the above cases, the receiving device specifies which carrier frequency currently used by the transmitting device is in the hobbing sequence, and determines the detection frequency. Synchronous acquisition technology that synchronizes the hopping timing with the transmitting side is important. As one of the conventional hopping synchronization methods, for example, as shown in FIG. The receiving device is a hopping sequence of F (1), F (2), …… F (j), F (j + 1), …… F (n). And the receiving device stops the frequency hopping operation and monitors the detection output while maintaining the detection frequency at a specific frequency (hereinafter referred to as a standby frequency) f (w), and detects the detection output ( From the state change of the carrier sense output), it is detected that the carrier frequency of the received signal coincides with the standby frequency f (w) (in FIG. 1, the hopping frequency becomes F (j)). A standby hopping synchronization scheme J is known, in which a hopping operation is started, and it is confirmed that the transmission and reception side frequencies are continuously the same for a predetermined number of hops, and the state is shifted to a synchronization holding state. .

One example of such a standby-type synchronization acquisition technology is, for example, Takahiro Oie, et al. “Consideration on FH-SS Communication Synchronization Method with Frequency Standby”, IEICE Technical Report, vol.94, No. 281, spectrum spread 94-54, pp. L-6 (1994).

Figure 2 shows n types of frequencies that can be hopped, and carrier frequencies are successively changed by periodically repeating a hopping sequence consisting of n hops from F (l) to F (n). A relatively short-period frequency hopping pattern is shown.

In short-period hopping patterns, each frequency is used only once per cycle of the hopping sequence. Therefore, if the above-mentioned standby synchronization acquisition method is adopted in a communication system using a short-period hopping pattern, for example, the transmission side device ties immediately after the carrier frequency hops to the frequency next to the reception side standby frequency f (w). When the receiving device starts the synchronization acquisition operation by mining, it takes one cycle (n hops) of the hopping sequence before the receiver succeeds in carrier sensing. Also, during the period when the carrier frequency on the transmitting side matches the standby frequency, for example, when the reception of radio waves is disturbed by noise, Otherwise, there is a problem that the chance of carrier sensation does not come around.

In other words, in the conventional standby synchronization acquisition method, the maximum value of the required carrier sense time is proportional to the hopping sequence length (the number of hops n for one cycle). The longer the duration of each frequency (hereinafter referred to as the hop period) Th, the longer it takes to acquire the synchronization. For this reason, in a wireless communication system in which synchronization capture can be performed for a time much shorter than one cycle of the hopping sequence, the standby-type hobbing synchronization acquisition method is ineffective.

On the other hand, as an alternative to the standby-type hopping synchronization acquisition method, for example, as described in Japanese Patent Application Laid-Open No. Hei 6-261020, the hop period T h of the carrier frequency on the transmitting side is used. Among them, there is a “high-speed search-type synchronization acquisition method” in which the receiver S performs a high-speed hobbing operation on all frequencies of the hobbing sequence to find the carrier frequency of the received signal.

However, in the conventional high-speed search synchronization acquisition method, the hop period T h ′ on the reception side at the time of synchronization acquisition is determined by the relationship between the hop period Th on the transmission side and the number n of hop frequencies (T h ′ = T h / n) .For example, when the hopping interpulse T h 'on the receiving side becomes extremely short due to the high hopping speed on the transmitting side, the switching operation of the output frequency of the frequency synthesizer is switched. Technical issues such as not being able to catch up with the command or not being able to obtain sufficient carrier sense output. For this reason, the high-speed search method uses a special frequency at which the carrier frequency on the transmitting side is switched at a low speed. It is effective in hopping communication.

An object of the present invention is to provide a frequency hobbing wireless communication system and a carrier sense method capable of capturing a hobbing frequency in a short time.

Another object of the present invention is to provide a frequency hobbing operation capable of synchronizing the frequency hobbing operation on the receiving side with the transmitting side within an allowable time shorter than one cycle of the hobbing sequence. And a synchronization acquisition method.

Still another object of the present invention is to provide a transmission apparatus in which synchronization control information is transmitted within a predetermined number of hops prior to data transmission, and a reception apparatus which acquires synchronization of a hobbing frequency within the synchronization period. It is an object of the present invention to provide a frequency hobbing radio communication system which is completed and thereafter performs data reception, and a synchronization acquisition method suitable for the same.

Still another object of the present invention is to provide a radio communication system in which a transmitting apparatus periodically hops a carrier frequency in accordance with a predetermined hobbing sequence using n types of frequencies once each period. 1 cycle of

An object of the present invention is to provide a synchronization acquisition device g and a synchronization acquisition method capable of achieving synchronization acquisition during a predetermined number of frequency hobbing periods 遥 much shorter than (n hops). Disclosure of the invention

In order to achieve the above object, a method for synchronously acquiring frequency hobbing according to the present invention includes the steps of: providing a receiving apparatus with a hobbing frequency sequence defining a hop order for a plurality of different frequencies; A sense frequency sequence that defines the hop order for a limited number of frequencies at the hop position described above is useful, and the transmitting device transmits the transmitted signal in accordance with the same frequency sequence as the hopping frequency sequence on the receiving side. The carrier frequency is switched periodically, and the receiving device fast hops the receiving frequency according to the sense frequency sequence at a switching speed of approximately one cycle of the sense frequency sequence within the successive period of each carrier frequency. And the carrier sense succeeds at a specific sense frequency. Starting from the hop location corresponding to the specific cell Nsu frequency in the hopping frequency sequence, characterized in that it shifts the frequency hobbing operation in accordance with the hobbing frequency shea one Ke Nsu. In a preferred embodiment of the present invention, when the carrier sense is successfully performed at the specific sense frequency, the receiving apparatus sets the receiving frequency to the next hop starting from the hop position corresponding to the specific frequency in the hopping frequency sequence. The frequency is switched to the frequency of the position, and when a carrier is detected within a predetermined time, the operation shifts to a periodic frequency hopping operation according to the hopping frequency sequence. As the sense frequency sequence, for example, a sequence including a plurality of frequencies separated by a predetermined hop interval in the hopping frequency sequence is applied, and the number of sense frequencies forms, for example, the hopping frequency sequence. It is determined by the number of frequencies and the number of hops of the carrier frequency allowed for acquisition. In a preferred operation example of the wireless communication system to which the synchronization acquisition method of the present invention is applied, the transmitting device transmits a synchronization control packet including synchronization control information during a predetermined number of frequency hopping periods prior to data transmission. When the device s shifts to the frequency hopping operation according to the hopping frequency sequence, it adjusts the hopping timing by using the synchronization control information in the reception bucket. Note that the transmitting device may be notified of the number of remaining hops before the start of data transmission by the synchronization control bucket, and the receiving device S may control the start of the data receiving operation based on the information of the number of remaining hops. it can.

A frequency hobbing wireless communication system according to the present invention includes a frequency synthesizer for switching a frequency of an output signal, a detection circuit for detecting a received signal at an output signal frequency from the frequency synthesizer, and a processing circuit for processing an output signal of the detection circuit. A demodulation circuit that demodulates the received signal by performing the above operation; a low-speed hobbing control unit that instructs the frequency synthesizer to switch the frequency at a predetermined cycle according to a hobbing frequency sequence that defines a hop order for a plurality of different frequencies; and the hobbing frequency. In accordance with a sense frequency sequence that defines a hop order for a limited number of frequencies at discrete hop positions 中で in the sequence, the above-mentioned carrier frequencies are connected. The high-speed hopping control means for instructing the frequency synthesizer to switch the frequency at a switching speed of about one cycle of the sense frequency sequence during the control period 內, and the frequency synthesizer in the hopping mode by the high-speed hopping means. When a carrier is detected from the output of the detection circuit while outputting a specific frequency, hopping by the low-speed hopping means is started from a hop position corresponding to the specific frequency in the hobbing frequency sequence. The hobbing mode switching means for switching to the mode is lowered. Brief explanation of drawings

FIG. 1 is a diagram for explaining a conventional standby-type carrier sensing method, FIG. 2 is a diagram showing an example of a frequency hobbing sequence,

FIG. 3 is a diagram for explaining the relationship between a frequency hopping sequence, a hobbing synchronization period, and a data transmission / reception period in the wireless communication system according to the present invention, and FIG. 4 is a diagram illustrating a carrier sense method according to the present invention. FIG. 5 is a block diagram showing one embodiment of a main part of a transmission circuit in the wireless communication system of the present invention,

FIG. 6 is a block diagram showing one embodiment of a main part of a receiving circuit in the wireless communication system of the present invention,

FIG. 7 is a detailed view of the carrier sense circuit 40 shown in FIG. 6,

FIG. 8 is a diagram showing one embodiment of a hopping pattern table,

FIG. 9 is a diagram showing one embodiment of a sense pattern table,

FIG. 10 is a diagram for explaining the relationship between the frequency hopping sequence and the sense frequency sequence,

FIG. 11 is a diagram showing a transmission bucket during a hobbing synchronization period, and FIG. 12 is a diagram showing hopping performed by a receiving circuit in a wireless communication system of the present invention. This is a flowchart showing the synchronization acquisition procedure. Best form to carry out the invention

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 shows a relationship between a carrier frequency hopping sequence, a hopping synchronization period T s allowed for a receiving device, and a data transmission / reception period T d in the wireless communication system of the present invention.

Here, n types of carrier frequencies are used, and one cycle of the frequency hopping sequence consists of n hops from F (l) to F (n) until the carrier frequency hops from one frequency to the next. The period (hop period T h) is a length that enables data transmission of, for example, about a few symbols (bits). The total time of the hopping synchronization period T s and the data transmission / reception period T d is represented by It should be shorter than the sequence period.

In the example shown here, the hopping synchronization period T s is the 30 hop period from the third hop F (3) to the second hop F (32) in the hopping sequence, and the data transmission / reception period T d is Is the 100 hop period from the third hop F (33) to the first 32 hop F (133), and the period of “T s + T d” is one cycle of the hobbing sequence. Indicates that it is only one part.

What is important here is that the hopping synchronization period T s force is much shorter than the hopping sequence. Therefore, as in the case of observing the frequency change from one window provided on the time axis, within each hopping synchronization period Ts, only a part of the n types of frequencies constituting the frequency hobbing sequence is included. Cannot observe.

In the above example, T s <T d, but the relationship may be T s ≧ T d. Also, within one cycle time of the hopping sequence, the above hopping synchronization period A plurality of sets each including T s and the data transmission / reception period T d may be set. Conversely, T s may occupy a part of the hobbing sequence, and T d may occupy one or more periods spanning the next hopping sequence.

In order to achieve frequency synchronization capture within the hobbing synchronization period T s in the extremely limited time zone described above, in the present invention, as shown in FIG. Performs frequency hopping in high-speed mode at k times the speed. In this specification, each frequency applied to the frequency hopping in the high-speed mode executed by the receiving device is defined as a “sense frequency”, and a hopping sequence including a plurality of sense frequencies is referred to as a “sense frequency sequence”. I will say.

One sense frequency sequence consists of a limited number of sense frequencies discretely selected from a carrier frequency hopping sequence. The number k of the sense frequencies is determined by the relationship between the carrier frequency hopping sequence period and the hobbing synchronization period Ts, as described later. Each communication device is provided with a sense frequency sequence of a plurality of patterns (hereinafter referred to as a “sense pattern”) corresponding to a hopping pattern of a carrier frequency that can be used by the transmission / reception device.

In the example shown in FIG. 4, the sense frequency sequence is composed of k types of sense frequencies from the first hop f (l) to the kth hop i (k), and each hop period T During h, the sense frequency hopping is repeated at the speed of one cycle of the sense frequency sequence. The illustrated example shows that when the transmitting side sets the carrier frequency to the frequency of the third hop F (3) of the hopping sequence, it matches the frequency of the seventh hop f (7) of the sense frequency sequence. FIG. 5 is a block diagram showing a main part of a transmission circuit of a transmission-side communication device. In the figure, 1 1 is the transmission data 10 and the two signal sequences 1 2 (I) and 1 2 (Q) The output signals 1 2 (1) and 1 2 (Q) of the modulation circuit 11 are input to multipliers 13 A and 13 B, respectively, and are generated by the frequency synthesizer 19. Quadrature modulation is performed by an I signal component 19 (I) of the carrier 19 and a Q signal component 19 (Q) orthogonal thereto. The output of the multiplier is synthesized by the adder 14 and then transmitted as a radio signal via the band-pass filter 15 and the antenna 17.

Reference numeral 25 denotes a frequency hopping (FH) pattern memory which is useful for storing a plurality of frequency hopping sequences to be described later. One frequency hopping sequence is provided in accordance with a read signal 21 provided by the hopping controller 20. Information 22 indicating the frequency belonging to is read out one after another. The hopping control device 20 periodically reads out the frequency information from the FH pattern memory 25 and outputs this to the frequency synthesizer 19 as a frequency designation signal 23. The frequency synthesizer 19 switches the output frequency in response to the frequency designation signal 23.

FIG. 6 shows a main part of a receiving circuit of the receiving communication device.

The signal received by the antenna 30 passes through the band-pass filter 31 and is input to the two multipliers 32A and 32B. These multipliers 32 A and 32 B are supplied with orthogonal signal components 51 (1) and 51 (Q) of a detection signal 51 of a specific frequency generated by the frequency synthesizer 50, respectively. Thereby, quadrature detection of the received signal is performed. The signal components orthogonal to each other output from the multipliers 32 A and 32 B are converted into signals 34 (1) and 34 (1) whose harmonic components have been removed by low-pass filters (LPF) 33 A and 33 B. 34 (Q) is input to the demodulation circuit 35, the bit synchronization circuit 37, and the carrier sense circuit 40. The demodulation circuit 35 demodulates the input signals 34 (1) and 34 (Q) in synchronization with the bit clock 38 generated by the bit synchronization circuit 37, and generates the received data 36. Output.

55 is a hobbing control device that instructs the frequency synthesizer 50 to switch the frequency based on the frequency information 57 read from the FH pattern memory 60. Yes, and receives the bit clock 38 and bit synchronization completion signal 39 generated by the bit synchronization circuit 37, and the carrier sense signal 49 generated by the carrier sense circuit 40, and performs frequency hopping. Control behavior. The hopping control device 55 is connected to a host processor (not shown) via a bus 59. Reference numeral 56 denotes a read control signal given to the hopping pattern memory 60 by the hopping control device 55, and 58 denotes a frequency designation signal given to the frequency synthesizer 50 by the hopping control device 55.

FIG. 7 shows the configuration of the carrier sense circuit 40.

The signals 34 (I) and 34 (Q) from which the harmonic components have been removed by the LPFs 33 A and 33 B are input to the multipliers 41 A and 4 IB, and the respective signal values are squared. Thereafter, they are added by the adder 42. The output 43 of the adder 42 is compared with a reference value (¾ value) 45 by the comparing unit 44 and output as a carrier sense signal 49. When the carrier frequency of the received signal input from the antenna matches the frequency 51 of the detection signal output from the frequency synthesizer 50, the amplitude of the received signal (carrier) increases, and the adder output 4 3 Exceeds the standard value. If the carrier is detected in this manner, carrier sense signal 49 is turned on, and if not, carrier sense signal 49 is turned off.

FIG. 8 shows an example of the hobbing pattern table 61 stored in the FH pattern memory 60 of the receiving communication device. The transmitting device also stores a similar hobbing pattern table in the FH pattern memory 25.

A plurality of hopping frequency sequences identified by hopping pattern IDs (HP1 to HP) are stored in the hopping pattern memory 61. Each hopping frequency sequence defines the hop order of n types of frequencies (fl to fn), with one cycle being n hops from F (l) to F (n). As can be seen from the example shown, the hopping frequency sequences HP 1 to HPX are The different patterns define the hop order of frequencies ί 1-: f η.

FIG. 9 shows an example of the sense pattern table 62 stored in the F-pattern memory 60 together with the hobbing pattern table 61.

In the sense pattern table 62, a plurality of sense frequency sequences SPl to SPx each corresponding to the hopping frequency sequence Η Ρ 1 to Ρ Ρ X are recorded, and each of the sense frequency sequences SPl to SPx is recorded. x defines the order of hops of the sense frequency, with one cycle of k hops from f (l) to f (k).

The sense frequencies constituting the sense frequency sequence SP i are discretely selected from the corresponding hopping frequency sequence HP i, and the hop order of the sense frequency follows the hop order in the hobbing frequency sequence HP i . According to the present invention, while the transmitting device S is transmitting information on one carrier frequency in the hopping frequency sequence HP i, the receiving device sets a high frequency for one cycle of the sense frequency sequence SP i. The speed hobbing operation is performed, and the synchronization acquisition is completed within a predetermined number of frequency hopping periods by the transmitting device.

The switching speed of the sense frequency performed on the receiving side within one hop period Th of the carrier frequency, that is, the number k of the sense frequencies forming one sense frequency sequence SP i is included in one cycle of the hopping frequency sequence HP i It is determined by the number n of wave numbers to be transmitted and the number of hops j in the hopping synchronization period T s, and k is a value larger than an integer value obtained by dividing n by j.

In addition, as shown in FIG. 10, for example, as shown in FIG. 10, among the n frequencies of the hobbing frequency sequence HP i, the sense frequencies forming the sense frequency sequence SP i include k numbers located at n / k hop intervals from each other. Apply the frequency of

For example, if n = 1 0 0 0 and k = 10, then nZ k = 1 0 0.Therefore, the frequency at an arbitrary position F (q) in the hopping frequency sequence is selected as f (l). F (q + 100), F (q + 200), F at 100 hop intervals from (q + 300),... are sequentially selected as f (2), f (3), f (4), and so on.

If n / k is not evenly divisible, select k frequencies with intervals as integer values with the decimal part truncated. Therefore, the sense frequencies need not necessarily be at exact hop intervals in the hopping frequency sequence.

As described above, when the sense frequency sequence SP 1 is formed by a frequency discretely selected from the hobbing frequency sequence HP i, one of the sense frequencies SP n 1 and n Z k hops of the carrier on the transmitting side is generated. A carrier that matches the frequency appears, and the carrier sense always succeeds within a predetermined period.

FIG. 11 shows a synchronization control packet transmitted by the transmitting device S during the hopping synchronization period T s.

70 F (1), 70F (2) and 70F (3) are synchronization control buckets transmitted on the carriers of F (1), F (2) and F (3) of the hopping frequency sequence. Each synchronization control packet has a length of 32 bits, for example, and includes a fixed pattern section 71A for bit synchronization and a hopping marker section 71B. Information indicating how many hops after the packet is received into the data transmission / reception period Td is inserted into the hopping capability 71B. After the success, based on the hopping marker information detected from the received packet, the start of data packet transmission / reception operation is controlled. FIG. 12 shows a flowchart of the synchronization acquisition control executed by the hobbing control device 55.

First, the synchronous control device S55 sets a hopping pattern ID for frequency hopping in the same hopping sequence as the transmitting device (step 101). For example, the hobbing pattern ID may be such that the control device 55 reads a value set in a register from an external device, or may be obtained from a host processor via the bus 59. Hopping pattern ID Then, the hopping frequency sequence HP i to be used and the corresponding sense frequency sequence SP i are uniquely determined.

Then, after setting the value of the parameter indicating the hop position S in the sense frequency sequence SP i to the initial value “0” (step 10 2), the value of K is incremented by 1 (10 3) , K are determined to exceed the upper limit value k (104). If K is equal to or smaller than k, the sense frequency of the K-th hop f (K) in the sense frequency sequence SP i is read from the memory 60, a switch to this frequency is instructed to the synthesizer 50, and the timer is timed. Set t (105). Next, the output signal 49 of the carrier sense circuit 40 is checked, and it is determined whether or not the carrier can be sensed at the sense frequency of the K-th hop f (K) (106). If the carrier cannot be sensed, that is, if the carrier frequency of the received signal does not match the above-mentioned sense frequency, the system waits for the timer to time out (107), and returns to step 103 and thereafter. Repeat steps.

Thus, every time the time t elapses, the detection frequency hops one after another in the sense frequency order defined in the sense frequency sequence S Pi. Here, the hop interval t of the sense frequency is related to t ^ T h when the hop interval of the carrier is T h, and as a result, as described in FIG. In time, the hobbing operation in the high-speed mode is performed for all the sense frequencies of the sense frequency sequence SP i. If the value of the parameter K exceeds the upper limit value k, the process returns to step 102, initializes the value of K (K = 0), and repeats the operations from step 103.

If the carrier can be sensed at the sense frequency of the Κth hop f (Κ) (106), the hop position SF () of the same frequency as the above sense frequency is selected from the hopping frequency sequence HP i of the memory 60. X) is searched (108). Next, a parameter N for indicating the hop position g in the frequency sequence HP i After setting (109), the value of the parameter N is incremented by 1 (110), and it is determined whether the value of N has exceeded the upper limit n (111) ). If N exceeds n, set it to the initial value (N = 0) (1 1 2) and return to step 110.

If the value of the parameter N is equal to or less than the upper limit value n, the frequency of the N-th hop F (N) of the hopping frequency sequence HP i is read out, the switching to this frequency is instructed to the synthesizer 50, and the timer is set to the carrier frequency. The value of the hop period Th is set (111). The output signal 49 of the carrier sense circuit 40 is checked, and it is determined whether or not the carrier can be sensed at the frequency of the Nth hop F (N) (111). The carrier sense is repeated until the timer times out (1 15).

For example, as shown in FIG. 4, in the middle of the holding period T h of the frequency of hop F (3), the receiving side succeeds in carrier sensing with the sense frequency f (7), and immediately after that, step 11 If the frequency on the receiving side is switched to the frequency of the next hop F (4) of F (3) in step 3, the carrier on the transmitting side remains at the frequency of hop F (3), so carrier sense is interrupted. . The return of the carrier sense performed in the above steps 114 to 115 is to wait for the transmission side to switch to the frequency of the next hop F (4).

If there is no abnormal operation in the first carrier sense (106), the harm of successful carrier sense at the frequency of the N-th hop F (N) before the timer expires after the time Th has elapsed. However, if the carrier could not be sensed before the timer expired, return to step 102 and start over from the high-speed search.

As a result of the transmission side switching to the frequency of the Nth hop F (N), if the carrier is sensed in step 114, the timer is reset to the carrier frequency hop period Th. After (116), the timer operation is adjusted based on the bit clock output from the bit synchronization circuit 37 (bit synchronization processing: 117). As a result, the hobbing timing of the receiving apparatus and the transmitting apparatus S can be synchronized with the hop period Th.

Next, a hopping marker is detected from the output signal 36 of the demodulation circuit 35 (118), and when the timer times out (119), the reception packet is calculated from the above value of the power. It is determined whether or not this is the last synchronous control packet (120). If it is the last synchronous control packet, the process proceeds to step 128, and if not, the process proceeds to step 122.

Steps 121 to 127 are control operations for hobbing the reception frequency every period Th until the last synchronization control packet is received, and include steps 1 to n of the hop position parameters N. While incrementing by one in the range (121 to 123), the frequency of the Nth hop F (N) of the hopping frequency sequence HPi is read, and the synthesizer 50 is instructed to switch to this frequency. Then, the time Th is set in the timer (124). Each time a frequency hobbing is detected, a marker is detected (125), and when the timer times out (122), the process returns to step 121, unless the received packet is the last synchronous control packet. Repeat the above steps.

When the synchronization control bucket of the last hop of the synchronization period is received, frequency hobbing in the data transmission / reception period Td starting from step 128 is executed. First, the parameter C for controlling the number of hops in the data transmission / reception period T d is set to the initial value “1” (1 228), and then the hop position g The parameter N ranges from 1 to While incrementing by 1 each time (1 2.9 to 13 1), read the frequency of the N-th hop F (N) of the hopping frequency sequence HP i and instruct the synthesizer 50 to switch to this frequency. Set the value of the hop period Th in the timer Yes (1 3 2). When the timer times out after the time Th, the count parameter C is incremented (133), and it is determined whether or not the value of C exceeds a predetermined value K (TO) (135). As long as the value does not exceed the predetermined value K (TO), the flow returns to step 1 29 to repeat the hop operation to the next frequency.

When the last synchronization control packet is received in the synchronization control period T s, for example, in step 128, the upper processor may be notified that the data transmission / reception period Td has been entered.

In the above embodiment, the data transmission / reception period T d is a fixed-length period determined by the number of hops K (TO), but the length of the data transmission / reception period T d or the value of K (TO) is determined by the transmitting device. Alternatively, it may be specified in the data packet or message transmitted during the data transmission / reception period Td to the receiving device.

In the embodiment, when the value of the count parameter C exceeds a predetermined value K (TO), it is determined that the data transmission / reception period Td has passed, and the control sequence proceeds to the next step “NEXT”. However, for example, if the transmitting device continues to transmit a signalless carrier while periodically repeating frequency hopping with the same hopping frequency sequence HPi during a transmission suspension period, for example, The above-mentioned “fNEXT” step may be set to step 121 and wait for reception of a synchronization control bucket in the next synchronization period T s.

Also, for example, the transmitting device a notifies the receiving device of a hopping pattern ID to be used in the next communication by a message transmitted in the data transmission / reception period Td, and the next time a new hopping frequency sequence HP i ′ is used. When data transmission / reception is performed, the above “NEXT” step may be set to step 101, and the control operation starting from the high-speed search may be repeated on the receiving side. Even when the hopping pattern is not switched, the process may return to step 102 once after data transmission / reception. Also, for example, when the mobile station starts communication with the base station as the transmitting apparatus and the mobile station as the receiving apparatus, and performs data transmission from the mobile station in response to data received from the base station, the mobile station performs the data reception operation. If the frequency hopping is continued as it is and data transmission is performed using the output frequency of the frequency synthesizer 50 as a carrier, it is necessary to perform synchronization acquisition on the base station side as the receiving side device. In this case, both the base station and the mobile station store the sense pattern table 62 shown in FIG. 9 in the memory, and the synchronization control packet is transmitted from the mobile station for a predetermined period (T s) prior to data transmission. Then, data transmission is performed after that, and the base station performs synchronization acquisition by the sense frequency hopping of the high-speed mode described in FIG. 12 and then receives the data. It is sufficient to shift to low-speed mode frequency hobbing. Industrial availability

As can be understood from the above description, according to the present invention, the sense frequency sequence is formed by a limited number of frequencies discretely selected from the hopping frequency sequence, and the sense frequency sequence is formed within the hop period Th of each carrier of the received signal. By hopping the detection frequency in the high-speed mode at the switching speed of one cycle of the above sense frequency sequence, carrier sense is performed within a predetermined number of hopping periods of the carrier wave, and synchronous acquisition of the hobbing operation is quickly achieved. According to the present invention, a wireless communication system that performs frequency hopping in a relatively short-period sequence is effective for speeding up data transmission / reception operations.

Claims

The scope of the claims

1. A hobbing frequency sequence in which the hopping order is defined for a plurality of different frequencies, and a sense frequency sequence in which a hopping order is defined for a limited number of frequencies at discrete hop positions in the hobbing frequency sequence. And remember

The transmitting device periodically switches the carrier frequency of the transmission signal according to the same frequency sequence as the hobbing frequency sequence on the receiving side,

The receiving device performs high-speed hopping of the receiving frequency at a switching speed of approximately one cycle of the sense frequency sequence within the successive period of each of the carrier frequencies according to the sense frequency sequence, and carries at a specific sense frequency. When succeeding in the sensing, starting from a hop position corresponding to the specific sensed wave number in the hobbing frequency sequence and starting from the hop position, a low-speed hobbing operation according to the hobbing frequency sequence is started. Synchronous acquisition method of frequency hobbing.

2. When the carrier sense is successfully performed at the specific sense frequency, the reception frequency is switched to the frequency of the next hop position with the hop position corresponding to the specific frequency in the hobbing frequency sequence as a starting point. 2. The synchronous capturing method according to claim 1, wherein when a carrier is detected within a time period, a transition is made to a periodic frequency hopping operation according to the hopping frequency sequence.

3. The method according to claim 1 or 2, wherein a sequence of a plurality of frequencies separated by a predetermined hop interval in the hopping frequency sequence is applied as the sense frequency sequence. Synchronous acquisition method as described.

4. As the sense frequency sequence, the number of frequencies forming the hopping frequency sequence, the number of hops of the carrier frequency allowed for synchronization acquisition, and 3. The synchronization acquisition method according to claim 1, wherein a sequence consisting of a number of frequencies determined by the method is applied.

5. The transmitting device transmits a bucket including synchronization control information during a predetermined number of frequency hopping periods prior to data transmission,

The method according to claim 1, wherein the receiving apparatus adjusts hopping timing using the synchronization control information in a reception bucket when the apparatus shifts to a frequency hopping operation according to the hobbing frequency sequence. Item 5. The synchronization acquisition method according to any one of Items 1 to 4.

6. The transmitting device transmits a bucket including control information indicating the number of hops remaining until the data transmission period during a predetermined number of frequency hopping periods prior to data transmission,

When the receiving device shifts to a frequency hopping operation in accordance with the hobbing frequency sequence, the receiving device controls a start of a data receiving operation based on the control information in a reception packet. The synchronization acquisition method according to any one of claims 1 to 4.

7. In a frequency hopping wireless communication system that transmits and receives signals while periodically hopping a carrier frequency according to a predetermined hopping sequence,

A frequency synthesizer for switching the frequency of the output signal,

A detection circuit for detecting a reception signal at an output signal frequency from the frequency synthesizer;

A demodulation circuit that processes the output signal of the detection circuit and demodulates the received signal; and a low-speed hoc that instructs the frequency synthesizer to switch the frequency at a predetermined cycle according to a hobbing frequency sequence that defines a hop order for a plurality of different frequencies. Bing control means,

A limited number of discrete hop positions in the above hobbing frequency sequence High-speed hopping that instructs the frequency synthesizer to switch frequencies at a switching speed of approximately one cycle of the sense frequency sequence within the duration of each carrier frequency according to the sense frequency sequence that defines the hop order for the frequency. Control means;

If a carrier is detected from the output of the detection circuit while the frequency synthesizer is outputting a specific frequency in the hopping mode by the high-speed hobbing means, the frequency corresponds to the specific frequency in the hobbing frequency sequence. Hopping mode switching means for switching to the hopping mode by the low-speed hopping means starting from the hop position;

A frequency hopping wireless communication system comprising:

8. The hopping mode switching means instructs the frequency synthesizer to switch to the next frequency starting from a hop position corresponding to the specific frequency in the hopping frequency sequence for a predetermined time. 8. The frequency hobbing wireless communication system according to claim 7, wherein when the carrier sense circuit detects a carrier, the mode is switched to a hopping mode by the low-speed hobbing means.

9. In a frequency hopping wireless communication system that transmits and receives signals while periodically hopping the carrier frequency according to a predetermined hopping sequence, the receiving frequency is hopped at a predetermined period in synchronization with the switching of the carrier frequency at the transmitting device S. Hopping control device S for

A frequency synthesizer for switching the frequency of the output signal according to an instruction from the hobbing control device;

A demodulation circuit that processes the output signal of the detection circuit and demodulates the received signal; A carrier detection circuit for determining the presence or absence of a carrier based on the output signal of the detection circuit,

The hobbing control device,

A memory useful for storing a hopping frequency sequence that defines a hop order for a plurality of different frequencies and a sense frequency sequence that defines a hop order for a limited number of frequencies at discrete hop positions in the hobbing frequency sequence. Means,

High-speed hobbing means for instructing the frequency synthesizer to switch the frequency at a switching speed for approximately one cycle of the sense frequency sequence within the duration of each carrier frequency according to the sense frequency sequence;

Low-speed hobbing means for instructing the frequency synthesizer to switch frequencies at a predetermined period according to the hobbing frequency sequence;

If the carrier sense circuit detects a carrier while the frequency synthesizer is outputting a specific frequency in the hobbing mode by the high-speed hobbing means, a hop position corresponding to the specific frequency in the hobbing frequency sequence. And a hopping mode switching means for switching to the hopping mode by the low-speed hopping means starting from the location.

10. The hopping mode switching means instructs the frequency synthesizer to switch to the next frequency starting from a hop position corresponding to the specific frequency in the hopping frequency sequence for a predetermined time. 10. The frequency hopping wireless communication system according to claim 9, wherein when the carrier sense circuit detects a carrier, the hopping mode is switched to the low-speed hopping means.

1 1. The detection circuit, based on an output signal from the frequency synthesizer, Performing quadrature detection on the received signal,

10. The frequency hopping wireless communication system according to claim 9, wherein the demodulation circuit processes a quadrature detection signal output from the detection circuit to demodulate a received signal.

12. A bit synchronization circuit for generating a bit clock based on the output of the detection circuit, wherein the demodulation circuit demodulates a received signal based on the bit clock, and controls the hopping. 12. The frequency hobbing wireless communication system according to claim 9, wherein the device adjusts hopping timing based on the bit clock.

13. The frequency according to any one of claims 9 to 12, wherein the detection circuit includes a low-pass filter for removing a subharmonic component from a detection output signal. Hopping wireless communication system.