KR20010101495A - A short range, low power communications system and a method of operating the system - Google Patents

Abstract

The short range, low power communication system includes a plurality of transmit and receive base stations (RCM 1 to RCM 4) capable of communicating in an ISM band, where the base stations to which data packets are to be transmitted are at least one geographic area and / or a plurality. The data packet is transmitted as a low bit rate direct sequence spread spectrum (DSSS) signal at a spectrum allocation common to the countries of the country. Carrier sense multiple access (CSMA) protocols can be used to allow base stations to access the spectrum allocation.

Description

A short range, low power communications system and a method of operating the system

In many regions and countries of the world, a so-called ISM band of about 2.4 GHz is available for short range communications. Commonly known systems operating in the ISM band are direct sequence spread spectrum (DSSS) systems and frequency hopping spread spectrum systems. DSSS systems are mainly used for high bit rate systems providing 11Mb / s, and frequency hopping systems provide mainly 1Mb / s. However, because the distribution area must be closely controlled, products must be specifically created or set up for arbitrary regions and countries, and products are also neighboring countries in the same region that are not universally available and sometimes annoying users. Difficulties arise in regulations and requests between regions and countries that make it impossible to use even in

The invention is not absolute, but in particular a short range (typically up to 50 m) with applications in, for example, home radio control systems for operating household appliances and fittings using radio remote controls. And a low power (10 mW) communication system and a method of operating the system.

1 is a block schematic diagram of a wireless local area network (LAN).

2 is a block diagram illustrating an ISM frequency band and several assigned spectra.

It is an object of the present invention to provide a communication system for universally available home and interactive devices.

According to one aspect of the present invention, there is a method of operating a short range low power communication system comprising a plurality of base transceiver stations capable of communicating in an ISM band, wherein the base station to which the data packet is to be transmitted is at least one geographic The data packet is transmitted as a low bit rate direct sequence spread spectrum signal at a spectrum allocation common to the region and / or a plurality of countries.

According to a second aspect of the present invention, there is provided a short range low power communication system comprising a plurality of transmit and receive base stations communicating on at least one channel in an ISM band, wherein the base station is at least one geographical area and / or a plurality of base stations. Means for transmitting the data packet as a low bit rate direct sequence spread spectrum signal in a spectral allocation common to the nations of.

A second aspect of the invention also includes a plurality of transmit and receive base stations communicating on at least one channel of an ISM band, one of the base stations acting as a central controller, where each said base station is at least one geographic Means for responding to a transmission request for transmitting a data packet as a low bit rate direct sequence spread spectrum signal in a spectrum allocation common to a region and / or a plurality of countries.

The system according to the invention does not request to occupy the entire ISM band of 2.4 to 2.5 GHz so that the operating frequency or frequencies can be chosen at will. For the most widespread use, frequency allocation may be selected from some of the ISM bands that are common to many but not all countries, for example 2,446.5 to 2,4750.0 MHz. By using a suitable data rate and DSSS with a limited spreading factor, the spreading signal can easily match within the frequency assignments. By using DSSS additionally, robustness and coding gains in transmission are obtained.

In an embodiment of the method and system according to the invention, the transmitting base station uses a carrier sense multiple access (CSMA) protocol to access the spectrum allocation.

By operating the system made in accordance with the invention, the following potential benefits are obtained.

1. Extensive sales of products without regional differences that simplify design, logistic, application, and installation and reduce unit costs.

2. The flexibility of using equipment without the need to reconfigure all wireless links when traveling between or through countries, in accordance with their respective different regulations.

3. A possible commonly available short range communication channel that is useful within its rights and can be used, for example, to establish specific links for operating higher bandwidth applications in a manner consistent with local regulations.

The invention is now described in detail by way of example with reference to the attached drawings.

(Modes for Carrying Out the Invention)

The wireless LAN shown in FIG. 1 includes many operating devices OD1, OD2, OD3, and OD4 and a wireless remote controller RC. For convenience of description, the operating devices OD1 to OD4 each include a TV set, a set top box STB, a video cassette recorder VCR and a personal computer PC. The operating devices OD1 to OD4 each have a radio control module RCM 1 to RCM 4 which allows the operating device to be members of a wireless LAN which can be controlled by the user operating the wireless remote controller RC. It includes more.

The wireless remote controller RC is a microcontroller 10, a keyboard 12 constituting a man / machine (MMI) interface coupled to the microcontroller 10 and a radio coupled to the microcontroller 10. And a transceiver 14. The output power of the transmitter of the transceiver 14 is approximately 10 mW providing a typical line in the 50 m viewing range.

Each of the radio control modules RCM 1 to RDM 4 is substantially identical, and for simplicity, only the radio control module RCM 1 is described in detail. An antenna (or other radio signal propagation means) 20 is coupled to a radio transceiver 22 that can transmit and receive DSSS signals on one or more narrow band channels in the ISM band. The microcontroller 24 includes inputs / outputs coupled to the program ROM 26, a store 28 for storing spreading code, and a store 30 for storing data packets.

The transmission of digital data packets between the pair of operating devices OD1-OD4 is as low low power, low bit rate, signal channel DSSS signals. Carrier Sense Carrier which listens to the radio channel and sends its data packet to check whether the radio control module to be transmitted has any activity on the radio channel and whether there are no radio control module switches to transmit The channel is accessed by Sense Multiple Access (CSMA).

For flexibility of operation, the wireless LAN does not have several central controllers, and at least some of the wireless control modules OD1 to OD4 can operate as the central controller CC. For convenience of reference, these operating devices are called masters that can operate the devices. As an example, this assumes that the radio control module RCM 2 functions as a central controller CC. If a user with a wireless remote controller (RC) wants the TV set to be effectively connected to the VCR, the user selects the VCR on the remote controller (RC), accesses the channel, and the DSSS signal S1 is transmitted by the transmitter as the central controller. It is sent to the transceiver 22 from a functioning remote control module RCM 2. The central controller checks to see if there is no channel, which assumes that the transceiver transmits a DSSS link to both operating devices OD1 to OD4 which establishes signals S2. The radio control modules RCM 1 and RCM 3 establish a wideband data exchange link (WL) between them to enable picture and sound data from the VCR to be played on the TV set.

The selection of a radio channel or channels for use by a communication system made in accordance with the present invention is determined by considering the current spectrum allocations in the ISM band.

2 shows spectral allocation for the ISM band at 40 and USA and Europe (EUR) at 42, France (FR) at 44, Spain (ES) at 46, and Japan at 48. Show them. Ignoring the Japanese assignment 48, it will be understood that there is sufficient overlap between the different assignments 42, 44, 46 to achieve several common channels, 3.3 MHz each. As the Japanese allocation 48 extends down, sufficient common capacity is combined with a slide 48 conceptually extended to allow similarly specified products to operate in the USA, Europe, France, Spain, and Japan. Provided by assignments 42, 44, and 46. Even in the present regular situation, it is possible to match the overlapping area between the channel between 2,471 MHz and 2,475 MHz and the bottom end of the Japanese assignment 48 and the top end of the Spanish assignment 46.

Ideally, to reduce interference with microwave ovens, it is beneficial for any important services and applications that use the lower portion of the frequency sub-band.

A summary table of proposals for key parameters of a narrowband DSSS wireless communication system for use in the ISM band is presented below. Transmission on the channel may be initiated according to the CSMA protocol.

parameter value Contents Frequency band 2.4475-2.4735 GHz (26 MHz bandwidth) Use common frequencies assigned to ISM bands in USA and Japan. Spread Spectrum Type Direct sequence The complexity shifted to the digital domain allows for fast synchronization and uses only a portion of the 2.4 GHz band. Frequency channel Six Channels Spread at 4MHz One channel assigned for network registration purposes Chip Rate 2.2 Mchips / s 3.3MHz bandwidth of main lobe of transmitter Spreading code 11 Barker Sequence Modulation GFSK, modulation index 0.5 Constant envelope Supported Gross Bit Rate 200 kb / s

By having several frequency channels, it is possible to allocate each channel for certain tasks such as registration and establish communication channels between the operating devices.

In this specification and claims, the term “a” or “an” before an element does not exclude the presence of a plurality of such elements. In addition, the term "comprises" does not exclude the presence of other components and steps than those described.

Upon reading this description, other variations will be apparent to those skilled in the art. Such variations are already known in the design, manufacture, and use of low power short range communication systems and components thereof and have already been described herein. It may include other forms that may be used instead of or in addition to the forms described in.

The present invention is applicable to short range (typically up to 50 nm), low power (10 mW) communication systems suitable for use in home wireless control systems.

Claims (10)

A method of operating a short range low power communication system comprising a plurality of transmit and receive base stations capable of communicating in an ISM band, comprising: A base station to which a data packet is to be transmitted must have a low bit rate, direct sequence spread spectrum signal at spectrum allocation common to at least one geographic region and / or a plurality of countries. Short range low power communication system. 2. The method of claim 1, wherein said transmitting base station uses a carrier sense multiple access (CSMA) protocol to access said spectrum allocation. Method according to one of the preceding claims, characterized in that the spectrum allocation lies in a frequency band between 2,446.5 and 2,475.0 MHz. 4. A short range low power communication system operation according to claim 1 or 2 or 3, characterized in that the modulation is a Gaussian Frequency Shift Key (GFSK) with a modulation index of 0.5. Way. 5. The short range low-value method according to any one of claims 1 to 4, wherein the chip rate is 2.2 Mchips / s and the spreading code is an 11 chip Barker sequence. How a Power Communication System Works. 6. The short range low-value of claim 1, wherein the spectral allocation is characterized in that the channels comprise a plurality of channels, at least one of which is allocated for registration purposes. 7. How a Power Communication System Works. 6. A short as claimed in any preceding claim, wherein said spectrum allocation comprises a plurality of channels, at least one of which is allocated for establishing communication channels between transmitting and receiving base stations. Range How low power communication systems operate. A short range low power communication system comprising a plurality of base transceiver stations communicating over at least one channel in an ISM band, The base station includes means for transmitting the data packet as a low bit rate direct sequence spread spectrum signal in spectrum allocation common to at least one geographic region and / or a plurality of countries. A short range low power communication system, comprising a plurality of base transceiver stations communicating over at least one channel in an ISM band, one of the base stations serving as a central controller. Each said base station has a short range, with means for responding to a transmission request for transmitting a data packet as a low bit rate direct sequence spread spectrum signal in a spectrum allocation common to at least one geographic region and / or a plurality of countries. Low power communication system. 10. A short range low speed access method as claimed in claim 8 or 9, wherein each of the base transceiver stations has means for responding to a transmission request for performing carrier sense multiple access (CSMA) to access the frequency spectrum. Power communication system.