JP2003520488A - Dynamic frequency hopping system - Google Patents

Abstract

  (57) [Summary] A frequency hopping system that dynamically changes a frequency hopping band according to a channel or a command is disclosed. At the same time as the operating band changes, the output may also be changed so as to always meet the regulatory requirements of the country in which the system operates.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION

The present invention relates generally to wireless communication systems using frequency hopping.

[0002]

BACKGROUND OF THE INVENTION

The main advantage of a wireless communication system is that it does not require wires.
The disadvantage is that it does not require wires and operates in almost the same frequency band. Therefore, in wireless communication, one of the most important factors is that the boundaries of frequency bands are clear (clrearly spectrum). 1985
Year, by the Federal Communications Commission (FCC), the US Industrial Science and Medical (ISM) band (3 unlicensed bands 902-928MHZ, 2.4-2.483) for general communication purposes.
5 GHz, and 5.725-5.870 GHz) were assigned under Rule 15. Currently, thousands of ISM devices are on the market. However, thousands of wireless devices have not been announced because the band is unlicensed. For example, recently, a wireless standard called Bluetooth has become widespread. This Bluetooth standard is available at www.bluetooth.com and is incorporated herein by reference in its entirety. Recently, there are three unlicensed U-NII bands (Unlicensed National Information Infrastructure band) in the 5 GHz region that promise high data rates.
s) has received a great deal of attention. Frequency hopping systems are currently the most prevalent and most well studied in frequency hopping.

US Pat. No. 5,832,026, assigned to Motorola, Inc. of Schaumburg, Illinois and incorporated herein by reference in its entirety, has advanced FH with greater resistance to interference. Describes the system. However, such an approach is complicated and not suitable for mass-produced consumer equipment.

Other related prior art is described in US Pat. No. 5,862,142, assigned to Hitachi, Ltd. of Tokyo, Japan, which is incorporated herein by reference in its entirety. This patent describes the construction of a frequency hopping wireless local area network (WLAN) having a controlling base station that controls the hop timing of the carrier frequencies of other controlling base stations. This is convenient for frequency hopping WLANs, but the basic problem with co-existing devices has not been solved.

A system that searches for a set of frequencies that at least one transceiver can use, sends the set to other transceivers on the network, and employs frequency hopping in this set of frequencies is a Thomson- It is described in US Pat. No. 5,24,788, which is assigned to CSF Company and incorporated herein by reference in its entirety.

Further, a frequency hopping communication method in which the hopping frequency changes according to the number of counted errors is transferred to Sanyo Electric Co., Ltd. of Osaka, Japan, the entire contents of which are incorporated by reference in the US patent. No. 5,541,954. In this patent, errors at all hopping frequencies are counted, and if the error at a frequency exceeds a certain threshold, that frequency is not used.

US Pat. No. 5,657,343, assigned to Inte Digital Technology Inc. of Wilmington, Del., Discloses a system that divides the system bandwidth B into a set of N non-overlapping frequencies. There is. Each base station has N concentric regions, with each concentric region being arranged in one of the N frequency sets described above, in a divided coverage area.

In US Pat. No. 5,870,391 assigned to Canon of Tokyo, Japan, a controller is used, and instead of using a separate frequency for communication to each device, the controller is common for communication of control information. Discloses an FH system using the FH pattern of

Although a thorough investigation has been conducted on conventional methods of accessing multiple devices, it is believed that none of the prior art wireless systems operate in the same frequency band. Multiple access methods consider how the device (or user) can use that frequency based on the same protocol. However, these methods do not take into account how different wireless systems can co-exist in the same frequency band, nor can they. Each wireless system assumes that it can use all the bands. If no measures were taken, this would be a very depressing situation, which would ultimately adversely affect all wireless communication standards and, in turn, prevent users from accepting wireless technology. It also becomes. For example, as the number of wireless devices increases, their co-existence becomes impractical, which makes users hesitant to use wireless devices. This is especially important in home networking applications where the number of wireless devices is expected to grow exponentially over the next few years. Devices that transmit at relatively high power will get that data, and other devices that do not will not get such data. We call this a "big stick" policy. Devices with greater compression work well.

One attempt to "eliminate" the problems of coexistence and interoperability is a wireless personal area network (WPAN) and scientific model of WLAN devices installed in conventional home and office spaces. Based on the assumption that different systems are not likely to be used simultaneously. Not only does this solve any coexistence problems, but it is also unsuitable for home networking applications where all systems are likely to be used simultaneously.

Therefore, it is necessary to replace the aforementioned “compression” policy with a “good citizen” policy. What is needed here is a method and apparatus by which the bandwidth occupied by an FH system can be dramatically adjusted so that the FH system can coexist with other wireless systems within the same frequency band. is there.

[0012]

[Outline of the Invention]

It is an object of the present invention to disclose an improved frequency hopping system that allows the occupied band to be adjusted dramatically.

Another object of the present invention is to disclose a frequency hopping system capable of changing its occupied bandwidth according to channel conditions or commands.

Another object of the present invention is to disclose a frequency hopping system capable of changing the level of its output power when changing its occupied bandwidth.

Yet another object of the invention is to dramatically adjust its parameters, whether or not frequency hopping, to accommodate other wireless systems without adopting the “compression” policy described above. It is to disclose an FH system that adopts a possible "good citizen" policy.

[0016]

DESCRIPTION OF THE INVENTION

Specifically, we consider the operation of a frequency hopping system in the 2.4 GHz ISM band. The operation is almost the same in any band. The 2.4 GHz ISM band has a width of 8.35 MHz between 2.4 and 2.4835 GHz everywhere except Spain, France and Japan. (Here we describe actions in the United States and Europe that can perform actions similar to those performed in Spain, France and Japan).

At time t1, only the 1 MHz wide band around f1 is used. At the next time t2, another band of 1 MHz width centered on another frequency is used. Hopping is based on a pseudo-random sequence known only to the transmitter and the intended receiver. For Bluetooth systems, the hopping order is derived from the device address on the master side of the communication. The master side of the communication is the device that temporarily controls the communication and all devices are physically the same and can act as master. Since the hopping order is not known to other receivers, hopping is considered to be safe. In addition, one of the narrow bands of the 1 MHz wide channel, eg f1,
If is crowded, it is highly possible that the state of the next channel is good. The drawback of frequency hopping is that a signal that requires only 1 MHz for transmission spreads over the entire 80 MHz wide band. This not only wastes bandwidth, but essentially disables other wireless systems in the same ISM band. For example, considering the guard band for the Bluetooth standard, there are 79 hopping channels each having a width of 1 MHz. These channels are 2402 + K MHz, respectively, and K = 0, ..., 78.

The operation of the system according to the first embodiment of the present invention is as follows. The master side of the communication monitors the SNR of all channels. Next, the channel with the highest SN ratio is found, and the channel is notified to other devices. Further, further communication is performed on the selected channel without hopping the frequency to another channel. If the SN ratio of this channel gradually or suddenly deteriorates to the extent that reliable communication cannot be performed, the master side issues a command to the slave side, and frequency hopping is performed again in the previous band. . After that, detection of a single channel that can be used for reliable communication is performed again. In this system, frequency hopping is performed only during communication establishment or when a change of frequency channel has to be performed. That is, frequency hopping is not performed at any other time.

If frequency hopping is not performed, the output power must meet certain criteria. In the United States, the US Industrial Science and Medical (ISM) band is the Federal Communications Commissions Part 15.247 (spread spectrum) and 15.249 (low ERP).
) Is controlled by. The relevant FCC rules are shown in Table 1. If spread spectrum is not used, the output power is 50 mV / m at a distance of 3 m
Limited to (50mV / m at 3m). This output power is sufficient for applications such as wireless personal area networks, wireless home networks, etc., where reliable communication is typically required over distances of about 30 feet.

[0020]

[Table 1] The U-NII band referred to above is governed by United States Federal Communications Commission Rule Part 15.401 to 15.407 in the United States, which is shown in Table 2. Non-spreading operation can also be performed in this band. Also here, we
Mostly mentioning rules in the United States, similar rules exist in other countries. Therefore, the application of the present invention is not limited to the United States, and the system according to the present embodiment may be implemented in the same manner in the world.

[0021]

[Table 2] Clearly, the first embodiment of the invention has a number of advantages. First of all, this embodiment is spectrally very efficient, since the 1 MHz signal is transmitted only on the 1 MHz wide channel. Second, and very importantly, other channels can be used by other wireless systems with or without frequency hopping. For example, part of a wireless system may be a fast orthogonal frequency division multiplexing (OFDM) system. Third,
The solution proposed here is the simplest and most economical way to solve the problem of coexistence between wireless communication systems. Sophisticated error correction coding and equalization will improve the performance of all wireless systems, but even if such systems adopt a "compression" policy, their complexity and cost will be a major obstacle, and probably , Will not be used for mass production applications. Finally, the solution proposed here replaces "compression" policies with "good citizens" policies.

In the second embodiment of the present invention, instead of stopping hopping completely, the system can hop frequencies in a narrow band. For example, 2.4G
2402 + K MHz in the ISM band of Hz, where K is {0, ...,
Instead of hopping 79 sets of 78},
Can be implemented by limiting the value of to a set of closed sets of {0, ..., 78}. The rest of the band should be reserved for other wireless systems. This also makes it possible to achieve the object of the present invention. Also, since frequency hopping continues to be used even in a narrow band, the device is generally able to transmit at higher power than non-spreading devices, subject to the proper rules. According to a second embodiment, the wireless transceiver, for example the master side of the communication,
It determines which sub-band of the entire band to use based on the empty area of the spectrum. For example, if there are other "good citizen" wireless systems operating in the same band, most channels provide high signal-to-noise ratios. The transceiver can then select the channel that provides the highest signal to noise ratio. In another example of the second embodiment, the transceiver selects several channels depending on the requirements of the particular application. Therefore, it is possible to obtain a higher data rate. The operation of the wireless system according to the second embodiment is dynamic, and the state of the temporarily selected channel deteriorates, for example, S
Even if the N ratio decreases, the system returns to the operation of hopping all bands and selects another set of channels in good condition. Alternatively, the system may select a new set of channels without returning to hopping all bands. Such an operation is performed, for example, when only some channels have deteriorated in condition while other channels provide the S / N ratios that satisfy the conditions. The master side of the communication can send a new set of channels to other transceivers using only the free channels. Another feature of the second embodiment is that if there is a change in the number of channels used, the power can be adjusted to the level specified by the appropriate regulatory agencies if necessary.

Certain embodiments of the second embodiment can easily come up with an important exception to Bluetooth. Such standards support different numbers of hopping frequencies depending on the country of operation. But there are four exceptions to that, the rest of the world, including France, Spain, Japan, and the United States. For example, in Japan, this ISM band is only 23 MHz. Therefore, the hopping frequency in Japan is
It is decided to be a closed subset of {0, ..., 78}. Therefore, the Bluetooth device now has a built-in feature that allows it to hop on a set of four different channels. This facilitates the implementation of the second embodiment of the invention in at least the United States and the rest of the world.

In some examples, if multiple wireless devices operate in the same band (which is not uncommon in future home networking), one transceiver may use the channels or channels used for reliable communication. In some cases it is not possible to determine the set of channels. In such a case, these devices are controlled by a wireless hub or spectrum management controller. By using a method not described here, the spectrum management controller detects the appropriate channel or set of channels and sends them to the devices. That is, the spectrum management controller dynamically monitors the frequency band of interest and manages it.

The present invention may be embodied in other forms, without departing from the spirit of the essential characteristics. It is understood that the described embodiments are merely illustrative and not restrictive. The scope of the invention is, therefore, set forth by the appended claims rather than the foregoing description. All changes which come within the scope and range of equivalents of the claims are to be embraced within their scope.

[Brief description of drawings]

[Figure 1]   FIG. 1 shows the operation of a typical frequency hopping system.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CR, CU, CZ, DE, DK , DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, J P, KE, KG, KP, KR, KZ, LC, LK, LR , LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, R O, RU, SD, SE, SG, SI, SK, SL, TJ , TM, TR, TT, TZ, UA, UG, UZ, VN, YU, ZA, ZW (72) Inventor Si Prestwich             84084, Wes, Utah, United States             Jordan, W. Miraberg               Way 3491 (72) Inventor Todo Cooklev             Utah, United States 84117, Salt               Lake City, E. Apple             Rossum 2709 F term (reference) 5K022 EE04 EE11 EE21 EE31

Claims (14)

[Claims] 1. At least one other operating within a defined frequency band or multiple frequency bands based on a defined frequency hopping protocol and operating within said defined frequency band or multiple frequency bands. Wireless system capable of coexisting with an independent wireless system according to claim 1, comprising a transmitter operating according to the defined frequency hopping protocol, the transmitter operating according to the defined frequency hopping protocol. In order to limit, depending on the control signal, dynamically adjustable to a subset of frequencies within the defined frequency band or frequency bands (subset), and
Such a transmitter allows the system to operate even when co-existing with other systems operating simultaneously in the defined frequency band or in multiple frequency bands, in which the transmitter is in response to changing conditions or commands. A control signal generator for generating the control signal for dynamically controlling a part of frequencies within the defined frequency band or a plurality of frequency bands that operate according to the above. 2. The wireless system as set forth in claim 1, wherein the transmitter operates on a subset composed of only one frequency subband. 3. The wireless system as set forth in claim 1, wherein the control signal generator is
Operating by generating the control signal to monitor the plurality of frequency bands and operate the transmitter on one or more subbands from the plurality of frequency bands. . 4. The wireless system as set forth in claim 1, wherein the control signal generator is
Measuring power levels in the plurality of frequency bands and operating the transmitter on the subband measured as having the lowest power level,
It operates by generating the control signal. 5. The wireless system as recited in claim 1, wherein the transmitter is capable of adjusting its power as needed to stay within regulatory requiments. 6. The wireless system as set forth in claim 1, wherein the control signal generator is
Responding to an internally generated command signal. 7. The wireless system defined in claim 1, wherein the control signal generator is
Responding to an externally generated command signal. 8. At least one other operating within a defined frequency band or multiple frequency bands based on a defined frequency hopping protocol and operating within the defined frequency band or multiple frequency bands. Wireless system capable of coexisting with an independent wireless system of, comprising a receiver operating according to the defined frequency hopping protocol, the receiver operating according to the defined frequency hopping protocol. In order to limit, depending on the control signal, dynamically adjustable to a subset of frequencies within the defined frequency band or frequency bands (subset), and
Such a receiver allows the system to operate even when coexisting with other systems operating simultaneously in the defined frequency band or multiple frequency bands, in which the receiver is in response to changes in conditions or commands. A control signal generator for generating the control signal for dynamically controlling a part of frequencies within the defined frequency band or a plurality of frequency bands that operate according to the above. 9. The wireless system of claim 8, wherein the receiver operates on a subset composed of only one frequency subband. 10. The wireless system of claim 8, further comprising a transmitter for wirelessly communicating with the receiver operating according to the defined frequency hopping protocol, the transmitter comprising: It limits its operation based on a defined frequency hopping protocol, so that it can be dynamically adjusted for a subset of frequencies within said defined frequency band or multiple frequency bands depending on the control signal. Yes, this transmitter allows the system to operate even when coexisting with other systems operating simultaneously within the defined frequency band or multiple frequency bands, in which Generating the control signal to dynamically control a portion of the frequencies within the defined frequency band or multiple frequency bands operating in response to a command, etc. Has a control signal generator further, the system that has a plurality of communication pairs composed of the transmitter and the receiver, those characterized by. 11. The wireless system as recited in claim 10, wherein the control signal generator and the control signal generator optimize a wireless link between each pair of communicating receiver and transmitter, or , Regulation requirements for each wireless link (regulation requirements
) To generate a control signal for operating the corresponding transmitter and receiver in a plurality of bands whose size can be dynamically adjusted. 12. The wireless system of claim 11, wherein the transmitter can also operate as a receiver to configure multiple transceivers. 13. The wireless system of claim 12, wherein the transceiver is based on a protocol that enables the transceiver to dynamically hop from one operating frequency to the next at a rate. What works, is characterized by. 14. At least one other operating within a defined frequency band or multiple frequency bands based on a defined frequency hopping protocol and operating within the defined frequency band or multiple frequency bands. A wireless system capable of coexisting with an independent wireless system of at least one other independent system that is operable based on the defined frequency hopping protocol and that operates within the defined frequency band or multiple frequency bands. A transmitter capable of coexisting with said wireless system, and wherein said system is operable to coexist with other systems operating simultaneously within said defined frequency band or multiple frequency bands, therein. Transmitter operates in response to changing conditions or commands The order defined dynamically controlling the portion of the frequency of the frequency band or in multiple frequency bands, the method steps, further comprising a, and wherein for generating a control signal that.