JP3210949B2 - Spread spectrum communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of determining a frequency hopping sequence for performing periodic hopping at a frequency with little interference wave when performing radio transmission using a frequency hopping method. The present invention relates to a spread spectrum communication method used for wireless communication that performs autonomous decentralized control that allocates a channel in accordance with the method.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing a conventional frequency hopping sequence. In the figure, 1 is a hopping frequency, and 2 is a cycle of a hopping sequence. 3 is time t
_n-1 and the interference wave level at this time is 2
1 dBμ. The following Similarly 4 interference wave level and frequency at time t _n, the frequency and the interference wave level at time t _{n + 1} 5, the frequency and the interference wave level at time t _{n + 2} 6, 7 frequency Metropolitan interference wave level at time t _{n + 3} , 8 indicate the frequency and the interference wave level at the time tn _{+ 4} . As shown in this figure, it has been common practice to use a plurality of predetermined sequences as hopping sequences for each wireless station of a communication partner so as to minimize interference with other communication. When hopping sequences are allocated in advance for each wireless station in this way, the number of hopping sequences that do not interfere with each other is determined, so that storable traffic is determined. For this reason, when the traffic is biased to some of the wireless stations, the hopping pattern that can be used in the wireless station has been determined, so that no further measures can be taken. For this reason, in the autonomous decentralized control, a hopping sequence without giving or not giving a hopping sequence before starting communication in a radio station which is going to perform communication was searched and allocated without interference or with little interference. .

[0003]

However, according to this method of searching and allocating, when traffic increases, there is no hopping sequence whose interference is lower than an allowable value, and communication cannot be performed. Further, even if a hopping sequence is assigned, at a specific time when an interference wave is high, a channel overlapping with a channel used by another wireless station occurs in each cycle of the hopping sequence, thereby deteriorating transmission quality. Also,
Since the hopping does not correspond to the interference wave, the same hopping pattern cannot be used unless the interference is sufficiently small in consideration of a radio station having a sufficiently high desired wave level even if the desired wave level is low. For this reason, the frequency use efficiency was low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and enables radio communication using a frequency hopping system having good quality and good frequency utilization efficiency, and is as close as possible to an allowable interference wave level and to an allowable interference wave level. Since a frequency that is equal to or lower than the level is allocated, it is possible to provide a spread spectrum communication method in which the frequency use efficiency is improved.

[0005]

According to the present invention, when performing bidirectional wireless communication, a centralized control station that centrally manages hopping frequencies is not designated, but each wireless station performs autonomous control. A wireless station that performs autonomous decentralized control, where n (n is 2
Each cycle t _i (i = 1 to 1) between times at which the frequency is changed within one cycle of hopping the above number of times as one cycle
n), the interference level of the entire hopping frequency or a channel of a limited frequency is measured, and at each time t
_A hopping sequence is determined by allocating a frequency at which the interference wave level is lower than the predetermined interference wave level and the highest interference wave level for each _i . That is, after measuring the interference wave over the entire hopping cycle, the hopping sequence in which the interference wave does not interfere with each other in the hopping sequence by selecting the frequency having the highest interference wave level below a predetermined value. Is used.

[0006]

According to the present invention, the hopping pattern is determined according to the interference wave level, so that the frequency utilization efficiency is good, and the hopping sequence can be adaptively selected according to the interference situation, so that the transmission quality is improved. I can do it. In particular, in the autonomous distributed control, the hopping sequence must be selected autonomously, so that a sequence with less interference can be selected instead of a fixed sequence.

[0007]

FIG. 1 is a view showing a reference example of the present invention. In the figure, 1 is a hopping frequency, and 2 is a cycle of a hopping sequence. 3 is a frequency used for time t _n−1 ,
The interference wave level at this time is 10 dBμ. The following Similarly 4 interference wave level and frequency at time t _n, the frequency and the interference wave level at time t _{n + 1} 5, 6 time t
Frequency and interference wave level at _{n + 2} , 7 is time t
Frequency and interference wave level at _{n + 3} , 8 is time t
The frequency and the interference wave level at _{n + 4} are shown. In this example, the cycle of the hopping sequence is 4, and the hopping frequency is 4 waves. In practice, a hopping frequency is selected from four or more frequencies.

[0008] This selects the time _t at _{n f3, t} the _{n + 1 f4, t n +} 2 at f1 and _{t n + 3} at f2.

FIG. 2 is a flowchart for determining a hopping pattern according to the reference example of FIG. First, the interference wave level of the hopping frequency is measured (step 11).
A channel having the lowest measured interference wave level is searched (step 12). At each time, it is determined whether there is a plurality of frequencies or a single frequency having the lowest interference wave level (step 13), and if there are a plurality of frequencies, a random selection is made (step 14). It is determined that a channel to be used has been searched within the hopping sequence cycle (step 15). If not completed, the process returns to step 11 and continues.

As described above, the frequency having the lowest interference wave level is used. If there are a plurality of frequencies at which the interference wave level is the lowest or a measurable level or less, a frequency is randomly selected from the plurality of frequencies and used.

FIG. 3 shows an embodiment of the present invention.
This is an example where the allowable level of interference (default value) is 25 dBμ.
In the figure, 1 is a hopping frequency, and 2 is a cycle of a hopping sequence. Reference numeral 3 denotes a frequency used for the time t _n-1 , and the interference wave level at this time is 21 dbμ. Similarly, 4 is the frequency and interference wave level at time t _n , 5
Is the frequency and interference wave level at time t _{n + 1} , 6 is the frequency and interference wave level at time t _{n + 2} , and 7 is time t _n
Frequency and interference wave level at _{n + 3} , 8 is time t
The frequency and the interference wave level at _{n + 4} are shown. In this example, the cycle of the hopping sequence is 4, and the hopping frequency is 4 waves. At time _{t n f4, t n + 1} in f2,
At tn _{+ 2} , f3 is selected, and at tn _{+ 3} , f1 is selected. At any time, a channel having the highest interference wave level among the frequencies of the interference wave level lower than the predetermined value 25 dBμ is used.

FIG. 4 is a flowchart for determining a hopping pattern in the embodiment of FIG. First, the interference wave level of the hopping frequency is measured (step 11).
A channel (frequency) whose measured interference wave level is equal to or less than a predetermined value is searched (step 22). At each time, it is determined whether there is a plurality of frequencies or one frequency corresponding to this condition (step 23). If there are a plurality of frequencies, a frequency having the highest interference wave level is selected from the candidates (step 24). Alternatively, when there is no frequency lower than the predetermined value, it is determined (step 25) and the frequency having the lowest interference wave level is selected (step 26). It is determined that a channel to be used over the entire hopping sequence period has been searched (step 15).
Return to and continue.

As described above, the frequency at which the interference wave level is smaller than the predetermined value and the interference wave level is the highest is used.
When there are a plurality of frequencies that satisfy this condition, a frequency is randomly selected from the plurality of frequencies and used. 1
If there is only a wave, use that frequency.

FIG. 5 shows an example of an interference wave level detector used in the reference example of FIG. In the figure, reference numeral 30 denotes an input terminal of a reception signal from a receiver, 31 to 33 denote bandpass filters (abbreviated as BPFs) which pass interference waves in the frequency band for each hopping frequency, and 34 to 36 denote interference wave levels. Is a power measuring device for measuring the interference wave power, 38 is a comparator for searching for a frequency having the lowest interference wave level from the result of the measurement of the interference wave power, and 39 is a comparison result indicating which frequency has the highest interference wave level. It is a terminal that outputs whether it is low.
With such a configuration, a hopping sequence having the lowest comparison wave level can be determined.

FIG. 6 shows an example of an interference wave level detector used in the embodiment of the present invention shown in FIG. In FIG.
Is an input terminal of a reception signal from the receiver, 31 to 33 are band-pass filters (abbreviated as BPF) for passing an interference wave in the frequency band for each hopping frequency, and 34 to 36 are for measuring an interference wave level. The power measuring device 37 has a reference interference wave level 37 as a reference for a predetermined comparison, and 40 has a lower than the reference value of the reference interference wave level 37 and has the lowest interference wave level from the result of comparing the measurement results of the interference wave power. A comparator 39 for searching for a high frequency is a comparison result output terminal for outputting which frequency has the lowest interference wave level as a comparison result. With such a configuration, a hopping sequence with the lowest interference wave level can be determined.

[0016]

As described above, according to the present invention,
Since a frequency that is as close as possible to the allowable interference wave level and equal to or lower than the allowable interference wave level is assigned, the frequency use efficiency increases. In addition, since a hopping pattern with good transmission quality can be determined according to the state of the interference wave, even in autonomous distributed control, wireless communication using a frequency hopping scheme with good quality and high frequency use efficiency is possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a reference example of the present invention.

FIG. 2 is a flowchart for determining a frequency hopping pattern according to the reference example of FIG. 1;

FIG. 3 is a diagram showing an outline of an embodiment of the present invention.

FIG. 4 is a flowchart for determining a frequency hopping pattern according to the embodiment of FIG. 3;

FIG. 5 is a block diagram of an example of an interference wave detector used in the reference example of FIG. 1;

FIG. 6 is a block diagram of an example of an interference wave detector used in the embodiment of FIG.

FIG. 7 is a diagram illustrating a conventional frequency hopping sequence.

[Explanation of symbols]

1 Frequency band for hopping 2 Period of hopping sequence 3 Frequency used at time t _n-1 and interference wave level of that frequency 4 Frequency used at time t _n and interference wave level of that frequency 5 Frequency used at time t _{n + 1} And the interference wave level at that frequency 6 The frequency used at time t _{n + 2} and the interference wave level at that frequency 7 The frequency used at time t _{n + 3} and the interference wave level at that frequency 8 The frequency used at time t _{n + 4} and the interference at that frequency Wave level 30 Received signal input terminal 31-33 Bandpass filter 34-36 Power measuring device 37 Reference interference wave level 38,40 Comparator 39 Comparison result output terminal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/69-1/713 H04J 13/00-13/06 H04Q 7/36

Claims (1)

(57) [Claims] 1. A spread spectrum communication method for performing communication in a predetermined sequence while changing the frequency at predetermined time intervals, wherein a central control station that centrally manages hopping frequencies when performing two-way wireless communication is designated. Rather, the wireless station performs autonomous distributed control in which each wireless station performs autonomous control.
(N is an integer of 2 or more) hopping times as one cycle, and each time t between times when the frequency is changed within that cycle.
_i (i = 1 to n), the interference level of the entire hopping frequency or a channel of a limited frequency is measured, and at each time t _i , the interference wave level is lower than the predetermined interference wave level value and the most. A spread spectrum communication method, wherein a hopping sequence is determined by assigning a frequency having a high interference wave level.