JP2003069454A - Spread spectrum wireless communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spread spectrum wireless communication system that prevents an undesired radio wave from being transmitted in the standby state of a slave side communication device so as to reduce a standby state average consumed current. SOLUTION: The spread spectrum wireless communication system consists of a master side communication device 1 and a slave side communication device 2 and conducts communications by using frequency hopping spread spectrum processing. The master side communication device 1 sets itself to a full frame transmission mode when establishing synchronization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum wireless communication device comprising a master side communication device and a slave side communication device and performing communication by frequency hopping / spread spectrum.

[0002]

2. Description of the Related Art In recent years, a wireless communication device using a spread spectrum communication system has rapidly spread, and has become widely used as a product such as a wireless LAN and a cordless telephone in general households. The spread spectrum method is characterized by excellent interference resistance and confidentiality. In addition, the US FCC (Fede
ral Communications Commi-
Institutions around the world, such as Ssion, are using ISM band (Industrial,
Scientific and Medical Ban
Many countries have released d) and allowed a larger transmission output than narrow-band modulated radio waves. In this case, in addition to the above-mentioned interference resistance and confidentiality, in terms of communication distance, it is much more advantageous than a device using narrow band modulation. Among the spread spectrum communication systems, the frequency hopping system is said to be particularly resistant to interference with other communication systems, and standardization such as Bluetooth is also active. On the other hand, it has a drawback that the time required for establishing synchronization is longer than other systems, which is disadvantageous in terms of battery life of the portable device.

FIG. 1 is a block diagram showing a general spread spectrum wireless communication apparatus using a frequency hopping spread spectrum communication system.

In FIG. 1, reference numeral 1 is a master side communication device 1,
Reference numeral 2 is a slave side communication device 2. The roles of the master-side communication device 1 and the slave-side communication device 2 may be fixed, but both the communication devices 1 and 2 have transmitters.
In some systems, the person who sends the call becomes the master and the roles are switched.

A procedure for establishing synchronization in the spread spectrum wireless communication apparatus thus configured will be described with reference to FIGS. 6 and 7. 6 (a) and 6 (b) are timing charts showing the behavior of the slave communication device 2 during standby, and FIG.
(A), (b) is a timing diagram which shows a synchronization establishment method.

The slave side communication device 2 basically operates the receiver continuously on one channel (fixed channel) in order to wait for a signal from the master side communication device 1. However, particularly in the case of a battery-powered portable device, it is necessary to strictly limit the average current consumption.
As shown in (b), the short time T2 in the constant period T1
Is generally set to a reception mode for operating the receiver, and the remaining time (T1-T2) is generally set to a standby mode in which current consumption is suppressed as much as possible. Cycle T to operate receiver
1, the minimum required cycle is often determined by each application, and the time length T2 of the reception mode of the slave communication device 2 is at least the time required for the master communication device 1 to scan all channels once. T3 or more is necessary, and if it is less than T3, the signal of the master side communication device 1 may be overlooked. The average current consumption mainly depends on the length of time T2 in the reception mode and how the current in the standby mode is suppressed. This is not particularly different between the frequency hopping method and other communication methods.

By the way, in a communication system in which the master side communication device 1 is arranged in advance so that the channel through which the signal is transmitted can be understood to some extent, the transmitter of the master side communication device 1 is prioritized in advance from 1 to N channels. Since the channel is taken out and transmitted, the receiver of the slave side communication device 2 can operate the receiver by giving priority to the channel which is known to some extent, and therefore the receiver of several frames to a dozen or more frames is required. It is often possible to establish synchronization in time.

However, in the frequency hopping spread spectrum system, in most cases, each country has its own restrictions on the minimum number of hopping channels and the time for occupying channels. This limitation is no exception when establishing synchronization, and the master side communication device 1 must transmit while hopping a frequency matching the limit, and the slave side communication device 2 also operates the receiver according to this. I have to let you.

FIG. 7 shows a conventional method for establishing synchronization in the spread spectrum wireless communication apparatus of FIG. 1, in which the transmission frame and the reception frame of both are equal in length t (that is, time division duplexing with a duty ratio of 50%). Method)). In this example, when the master-side communication device 1 hops on the channel on which the slave-side communication device 2 is waiting and discovers the signal, the slave-side communication device 2 also starts hopping on the same frequency table and communication is started. It At this time, the slave side communication device 2 must continuously receive and monitor the time when the signal of the master side communication device 1 visits the channel at least once. The shortest time is a hopping pattern in which all the hopping channels are simply rotated once to form one cycle, but even in this case, as shown in FIG. 7, T ≧ 2 × t × N ... ... (1). That is, it is necessary to continuously operate the receiver and monitor the signal from the master-side communication device 1 for a time of 2 × t × N or more. Here, T is the monitoring time, t is the transmission frame length (= reception frame length), and N is the number of hopping channels. For example, t = 1 ms, N = 75
In the case of a channel, it is necessary to receive for T = 150 ms or more. On the other hand, in a communication system having a similar frame structure and a channel to which the master side communication device 1 sends a signal to a certain extent, it takes about several ms to tens of ms.

As described above, in the conventional frequency hopping / spread spectrum communication system, the receiver must be operated for a very long time as compared with other systems to monitor the signal from the master side communication device 1. On the other hand, a method is generally used in which only the first synchronization is established using the above method, and thereafter, the signal is transmitted from the master side communication device 1 periodically even during standby, so that the synchronization is always secured. This is not a preferable method from the standpoint of interference because it emits radio waves periodically other than when actually communicating.

[0011]

As described above, in the frequency hopping / spread spectrum communication system in the conventional spread spectrum wireless communication device, when the slave side communication device 2 waits for a signal from the master side communication device 1, As compared with other systems, the receiver needs to be operated for a very long time, which is disadvantageous in terms of battery life of the portable device. As another method, as described above, there is a method of periodically performing communication in order to maintain synchronization even during standby, but this is not a good method in terms of interference.

In this spread spectrum wireless communication device,
It is required to prevent unnecessary electric waves from being transmitted during standby of the slave communication device and reduce average standby current consumption.

In order to satisfy this demand, the present invention provides a spread spectrum wireless communication device capable of reducing unnecessary standby current consumption by preventing unnecessary radio waves from being transmitted by the slave communication device during standby. The purpose is to

[0014]

In order to solve the above problems, a spread spectrum wireless communication device of the present invention comprises a master side communication device and a slave side communication device, and spread spectrum communication is performed by frequency hopping spread spectrum. The master communication device, which is a wireless communication device, is configured to set itself to the all-frame transmission mode when synchronization is established.

As a result, it is possible to obtain the spread spectrum wireless communication device capable of preventing the slave side communication device from transmitting unnecessary radio waves during standby and reducing the average current consumption during standby.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A spread spectrum wireless communication device according to claim 1 of the present invention comprises a master side communication device and a slave side communication device, and performs spread spectrum wireless communication device by frequency hopping / spread spectrum communication. However, the master-side communication device sets itself to the all-frame transmission mode when synchronization is established.

With this configuration, it is possible to go around a predetermined hopping channel in a short time (about half of the conventional time), and to shorten the standby reception time of the slave side communication device (reception mode time in FIG. 6). Therefore, the standby current consumption of the slave side communication device can be reduced, and the life of the battery can be extended when the slave side communication device is a portable device.

A spread spectrum wireless communication apparatus according to claim 2 is the spread spectrum wireless communication apparatus according to claim 1, wherein the slave side communication device hops every other channel on the hopping table. It is designed to set itself to the alternate transmission / reception alternating communication mode for only a few frames.

With this configuration, in every other transmission / reception alternating communication mode, there is an effect that a response signal can be transmitted to the master communication device at a predetermined timing to quickly establish synchronization.

A spread spectrum wireless communication apparatus according to a third aspect is the spread spectrum wireless communication apparatus according to the first aspect, in which the slave side communication device is a signal from the master side communication device in alternate transmission / reception alternating communication mode. When it becomes impossible to receive the fixed channel continuous reception mode, it immediately returns to the fixed channel continuous reception mode and continues the fixed channel continuous reception mode while the master side communication device in the all frame transmission mode makes at least one round of the hopping channel. is there.

With this configuration, the slave side communication device erroneously detects the signal from the master side communication device and changes the mode,
In the recovery process after the signal from the master-side communication device cannot be received, the synchronization-establishing process can be recovered without making a mistake of hopping of the master-side communication device.

A spread spectrum wireless communication apparatus according to a fourth aspect is the spread spectrum wireless communication apparatus according to the first aspect, wherein the master-side communication device establishes synchronization.
The alternate transmission / reception alternating communication mode for hopping every other channel on the hopping table is periodically added to the all-frame transmission mode.

With this configuration, in every other transmission / reception alternating communication mode, the signal from the slave side communication device can be received and the transmission / reception alternating communication mode can be rapidly shifted, so that the synchronization can be quickly established. Have an effect.

According to a fifth aspect of the spread spectrum wireless communication device of the present invention, in the spread spectrum wireless communication device of the fourth aspect, the master side communication device responds from the slave side communication device in the alternate transmission / reception communication mode. When no signal can be received, the system immediately returns to the all-frame transmission mode.

With this configuration, when the response signal from the slave side communication device cannot be received in the alternate transmission / reception alternating communication mode, the mode immediately returns to the full frame transmission mode, so that it is possible to go around a predetermined hopping channel in a short time. Therefore, the standby reception time of the slave communication device can be shortened, so that the standby current consumption of the slave communication device can be reduced.

A spread spectrum wireless communication device according to a sixth aspect is the spread spectrum wireless communication device according to any one of the first to fifth aspects, wherein the master side communication device and the slave side communication device are master side communication devices. When the slave side communication device waits for a signal from the machine, the frequency of the signal to be waited for is determined beforehand as the frequency of either the even channel or the odd channel on the hopping table.

With this configuration, when shifting to the transmission / reception alternating communication mode in which every other channel on the hopping table is hopped, the frames of the master side communication device and the slave side communication device do not shift. It has the effect of being able to.

FIG. 1 shows an embodiment of the present invention.
~ It demonstrates with reference to FIG.

(Embodiment 1) A spread spectrum radio communication apparatus according to Embodiment 1 of the present invention has the configuration shown in FIG.

In the spread spectrum radio communication apparatus having such a configuration, the master side communication device 1 completes hopping for one round in half the time as compared with the conventional method. Will be explained. Figure 2
FIG. 2A is a timing diagram showing mode 0 (fixed channel continuous reception mode), FIG. 2B is a timing diagram showing mode 1 (all frame transmission mode), and FIG. FIG. 2D is a timing chart showing the alternate transmission / reception alternating communication mode, and FIG. 2D is a timing chart showing the mode 3 (transmission / reception alternating communication mode). Further, FIG. 3A is a timing diagram showing modes in the master communication device 1, and FIG. 3B is a timing diagram showing modes in the slave communication device 2.

Next, the modes will be described in detail.

First, mode 0 is a mode in which continuous reception is performed without changing the frequency, and since the slave side communication device 2 monitors the signal from the master side communication device 1, the receiver is operating, The mode is the same as the conventional technique. In mode 1, all channels are hopping, but all frames are used for transmission and the receiver is not operated. Further, the mode 2 is a mode in which transmission and reception are alternately performed as in normal communication, and is a mode in which hopping is performed every other channel. Finally, mode 3 is a normal communication mode in which transmission and reception are alternately performed and hopping is performed on all channels.

FIG. 3 shows a method of actually establishing synchronization using each mode of FIG.

When a communication start instruction is issued, the master side communication device 1 first uses all frames in mode 1 for transmission and hops all channels (FIG. 3 (a)). In the conventional method of FIG. 7, all the channels are hopped by using up to the received frame as the transmission frame. Therefore, in mode 1, compared with the conventional method,
You can complete one round of the hopping channel in half the time. At this time, the slave communication device 2 first waits for a signal from the master communication device 1 in mode 0 as in the conventional method (FIG. 3B). At this time, it is necessary to promise in advance between the master side communication device 1 and the slave side communication device 2 whether the waiting channel is an even channel or an odd channel on the hopping table. This is necessary for the transmission / reception frames of the master-side communication device 1 and the slave-side communication device 2 to match well at the time of transition to the mode 2 described below. The channel the master communication device 1 is waiting for (5 in this case)
When the slave side communication device 2 discovers the signal of the master side communication device 1, it shifts to mode 2 and starts hopping every other channel. The slave-side communication device 2 continues to receive the signal from the master-side communication device 1 and can confirm the ID and the like, but the master-side communication device 1 does not operate the receiver, and thus receives the response signal from the slave-side communication device 2. Not possible, the system will remain in this state for a while.

Here, the master-side communication device 1 uses all frames for transmission in mode 1 to hop all channels, but periodically switches to mode 2 to send a response signal from the slave-side communication device 2. To monitor. When the response signal is found, the ID information and the like are exchanged in the mode 2 for several frames as they are, and then both of them shift to the mode 3 to start normal communication.

Basically, the master side communication device 1 can complete one round of the hopping channel in half the time as compared with the conventional method, and the monitoring time T of the slave side communication device 2 for monitoring the signal is: T ≧ = t × N (2), which means that the receiver may be operated for half the time of the conventional method. To be precise, as will be described later, the time for the master side communication device 1 to monitor in the mode 2 is added to this.

Regarding the cycle in which the master side communication device 1 is switched to the mode 2 and the receiver is operated, FIG. 3 shows an example in which the operation is carried out exactly once for the number N of hopping channels. This can be adjusted according to the circumstances of each application.

FIG. 4 is a timing chart showing the behavior when the signal from the slave communication device 2 cannot be found when the master communication device 1 periodically switches to the mode 2 to operate the receiver. Yes, if several frames are received and cannot be found, the mode 1 is returned to again. It should be considered that the number of frames at this time is included in the time required for the master-side communication device 1 to complete one round of the hopping channel, and the time for the slave-side communication device 2 to operate the receiver is also reduced by this amount. Need to stretch. Therefore, the monitoring time T becomes T ≧ t × (N + M) ... (3), where M is the number of operation frames in the mode 2 of the master-side communication device 1. Therefore, it is desirable that the master-side communication device 1 periodically switches to the mode 2 to minimize the number of frames for operating the receiver.

FIG. 5 is a timing chart showing the behavior when the slave side communication device 2 once erroneously recognizes the signal of the master side communication device 1 and thereafter judges that it is an error and returns to the mode 0 again. For example, if the condition for the slave communication device 2 to shift from mode 0 to mode 2 is set to a relatively unfavorable condition such as a coincidence of a synchronization word (SyncWord), erroneous detection due to noise is relatively likely to occur. After shifting to mode 2, I
If a discrepancy in D etc. is detected, promptly set the mode 0
Need to go back to. At this time, any channel may be returned, but in order not to pass the signal of the master communication device 1 during this erroneous detection processing, the mode 0 continuous reception after returning is still T ≧ It is necessary to continue for t × (N + M) ... (4). That is, even if such a malfunction occurs, by setting the continuous reception period of the slave-side communication device 2 to T, it is possible to return to the synchronization establishment process without passing the signal of the master-side communication device 1, and the synchronization can be performed in the shortest time. Can be established.

As described above, according to the present embodiment, the spread spectrum radio communication device is composed of the master side communication device 1 and the slave side communication device 2 and performs communication by frequency hopping / spread spectrum. The communication device 1 sets itself in the all-frame transmission mode when establishing synchronization, so that the communication device 1 can operate for a short time (about half the time of the conventional method).
Since it is possible to go around a predetermined hopping channel and shorten the standby reception time of the slave side communication device 2, it is possible to reduce the standby current consumption of the slave side communication device 2 and the slave side communication device. When 2 is a portable device, the life of the battery can be extended.

Further, the slave side communication device 2 sets itself every few frames in the alternate transmission / reception alternating communication mode in which every other channel on the hopping table is hopped to set the alternate transmission / reception alternate communication mode. In, the signal of the response can be transmitted to the master side communication device 1 at a predetermined timing to quickly establish the synchronization.

Further, when the slave side communication device 2 cannot receive the signal from the master side communication device 1 in the alternate transmission / reception alternating communication mode, it immediately returns to the fixed channel continuous reception mode and the all frame transmission mode. By continuing the fixed channel continuous reception mode while the master communication device 1 makes at least one round of the hopping channel, the slave communication device 2 erroneously detects the signal from the master communication device 1 and changes the mode. In the recovery process after the signal from the master-side communication device 1 can no longer be received, it is possible to return to the synchronization establishment process without passing the hopping of the master-side communication device 1.

Further, the master side communication device 1 periodically adds the alternate transmission / reception alternating communication mode for hopping every other channel on the hopping table to the all frame transmission mode when establishing synchronization. By 1
In the alternate transmission / reception alternating communication mode, the signal from the slave side communication device 2 can be received and the transmission / reception alternating communication mode can be swiftly transitioned, so that the synchronization can be quickly established.

Further, when the master side communication device 1 cannot receive the response signal from the slave side communication device 2 in the alternate transmission / reception alternating communication mode, the master side communication device 1 immediately returns to the all-frame transmission mode, thereby transmitting and receiving every other frame. When the response signal from the slave communication device 2 cannot be received in the alternate communication mode, the mode returns to the all-frame transmission mode promptly, so that the predetermined hopping channel can be turned in a short time, and the slave communication device 2 is in the standby state. Since the reception time can be shortened, the standby current consumption of the slave communication device 2 can be reduced.

Further, when the slave side communication device 2 waits for the signal from the master side communication device 1, the master side communication device 1 and the slave side communication device 2 preliminarily set the frequency of the signal awaited in advance on the hopping table. By determining the frequency of either the channel or the odd-numbered channel, the master side communication device 1 and the slave side communication are performed when shifting to the transmission / reception alternating communication mode in which every other channel on the hopping table is hopped. It is possible to prevent the frame from the machine 2 from slipping.

[0046]

As described above, according to the spread spectrum wireless communication device of the first aspect of the present invention, the master side communication device and the slave side communication device are used to perform communication by frequency hopping spread spectrum. In the spread spectrum wireless communication device, the master-side communication device turns around the predetermined hopping channel in a short time (about half the time of the conventional method) by setting itself to the all-frame transmission mode when establishing synchronization. Since the standby communication time of the slave communication device can be shortened, the standby current consumption of the slave communication device can be reduced, and the battery length when the slave communication device is a portable device can be reduced. The advantageous effect that the life can be extended can be obtained.

According to the spread spectrum wireless communication device of the second aspect, in the spread spectrum wireless communication device of the first aspect, the slave side communication device hops every other channel on the hopping table. By setting itself every few frames in the alternate transmission / reception alternating communication mode, a response signal is transmitted to the master communication device at a predetermined timing in the alternate transmission / reception alternating communication mode to quickly establish synchronization. The advantage is that it can be done.

According to the spread spectrum wireless communication device of the third aspect, in the spread spectrum wireless communication device of the first aspect, the slave side communication devices are transmitted from the master side communication device in the alternate transmission / reception alternating communication mode. When the signal of is no longer received, the fixed channel continuous reception mode is promptly returned, and the fixed channel continuous reception mode is continued while the master side communication device in the all frame transmission mode makes at least one round of the hopping channel. When the slave side communication device erroneously detects the signal from the master side communication device, the mode is changed, and when the recovery process is performed after the signal from the master side communication device cannot be received, hopping of the master side communication device may occur. There is an advantageous effect that it is possible to return to the synchronization establishment processing without making a difference.

According to the spread spectrum wireless communication device of the fourth aspect, in the spread spectrum wireless communication device of the first aspect, the master side communication device selects a channel on the hopping table when synchronization is established. By alternately adding the alternate transmission / reception alternating communication mode that hops every other frame to the all frame transmission mode, in the alternate transmission / reception alternate communication mode, the signal from the slave side communication device is received to promptly perform the alternate transmission / reception. Since it is possible to shift to the communication mode, there is an advantageous effect that the synchronization can be quickly established.

According to the spread spectrum wireless communication device of the fifth aspect, in the spread spectrum wireless communication device of the fourth aspect, the master side communication device is transmitted from the slave side communication device in the alternate transmission / reception alternating communication mode. If the response signal from the slave side communication device cannot be received in the alternate transmission / reception alternating communication mode, the system immediately returns to the all-frame transmission mode by returning to the all-frame transmission mode immediately when the response signal is not received. Therefore, it is possible to go around the predetermined hopping channel in a short time, and it is possible to shorten the standby reception time of the slave side communication device, and thus it is possible to reduce the standby current consumption of the slave side communication device. The effect is obtained.

According to the spread spectrum wireless communication device of the sixth aspect, in the spread spectrum wireless communication device of any one of the first to fifth aspects, the master side communication device and the slave side communication device are masters. When the slave side communication device waits for the signal from the local communication device, the frequency of the signal to be waited for in advance is set to the frequency of either the even channel or the odd channel on the hopping table. When shifting to the transmission / reception alternating communication mode in which every other channel is hopped, it is possible to prevent the frames of the master-side communication device and the slave-side communication device from being shifted from each other, which is an advantageous effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing a general spread spectrum wireless communication device using a frequency hopping spread spectrum communication system.

FIG. 2A is a timing chart showing mode 0 (fixed channel continuous reception mode), (b) a timing chart showing mode 1 (all frame transmission mode), and (c) mode 2 (every other transmission / reception alternating communication mode). Timing diagram shown (d) Timing diagram showing mode 3 (transmission / reception alternating communication mode)

FIG. 3A is a timing diagram showing modes in a master communication device, and FIG. 3B is a timing diagram showing modes in a slave communication device.

FIG. 4 is a timing chart showing the behavior when a signal from a slave communication device cannot be found when the master communication device periodically switches to mode 2 and operates the receiver.

FIG. 5 is a timing chart showing the behavior when the slave side communication device erroneously recognizes the signal of the master side communication device once, judges that it is an error and returns to the mode 0 again.

FIG. 6A is a timing diagram showing the behavior of the slave communication device during standby. FIG. 6B is a timing diagram showing the behavior of the slave communication device during standby.

FIG. 7A is a timing diagram showing a synchronization establishing method. (B) Timing diagram showing the synchronization establishment method

[Explanation of symbols]

1 Master side communication device 2 Slave side communication device

Claims (6)

[Claims] 1. A spread spectrum wireless communication device comprising a master-side communication device and a slave-side communication device for performing communication by frequency hopping / spread spectrum, wherein the master-side communication device itself when synchronizing is established. Spread spectrum wireless communication device, characterized in that is set to the all frame transmission mode. 2. The slave side communication device sets itself for a few frames in alternate transmission / reception alternating communication mode in which every other channel on the hopping table is hopped. Spread spectrum wireless communication device. 3. The slave side communication device immediately returns to the fixed channel continuous reception mode when it becomes impossible to receive a signal from the master side communication device in the alternate transmission / reception alternating communication mode, and all the frames are received. The spread spectrum wireless communication apparatus according to claim 1, wherein the fixed channel continuous reception mode is continued while the master side communication device in the transmission mode makes at least one round of a hopping channel. 4. The master side communication device periodically adds an alternate transmission / reception alternating communication mode for hopping every other channel on a hopping table to the all frame transmission mode when establishing synchronization. The spread spectrum wireless communication device according to claim 1, wherein 5. The master-side communication device quickly returns to the all-frame transmission mode when it cannot receive a response signal from the slave-side communication device in the alternate transmission / reception alternating communication mode. The spread spectrum wireless communication device according to claim 4. 6. The master-side communication device and the slave-side communication device, when the slave-side communication device waits for a signal from the master-side communication device, the frequency of the signal to be awaited is previously stored on a hopping table. 6. The spread spectrum wireless communication device according to claim 1, wherein the frequency of either the even channel or the odd channel is determined.