WO2002007387A1

WO2002007387A1 - Communication module between a local radio data transmission network and a high speed radio network

Info

Publication number: WO2002007387A1
Application number: PCT/FR2001/002303
Authority: WO
Inventors: Olivier Guilbaud; Laurent Maleysson
Original assignee: Coronis Systems
Priority date: 2000-07-19
Filing date: 2001-07-16
Publication date: 2002-01-24
Also published as: FR2812149A1; FR2812149B1; AU2001276455A1

Abstract

The invention concerns a communication module for setting up communications between a high-speed low-power radio network equipment and a low-power transmission network equipment. It comprises: a first interface (3) with the high-speed low-power network (1) including: a transceiver (7); means for base band low-level processing (8); means for processing related to the high-speed network operating mode (9); a second interface (5) with the low-power data transmission network (2) including: a transceiver; means for base band low-level processing; means for managing the protocol(s) used by said low-power network (2); a software (4) providing interface between said two interfaces and designed to cause the low-power network (2) equipment to operate as high speed low power radio network equipment.

Description

COMMUNICATION MODULE BETWEEN A LOCAL RADIO DATA TRANSMISSION NETWORK AND A HIGH SPEED RADIO NETWORK.

The invention relates to a communication module for establishing communications between a local radio data network and a broadband radio network.

More specifically, the invention is intended to provide interfacing between a local radio data transmission network and a Bluetooth type network. The Bluetooth network is a wireless data transmission network, making it possible to link together equipment for the exchange of data at high speeds.

This Bluetooth network is the subject of a specification, called "Specification of the Bluetooth System - Core", the current version of which is version 1.1 of February 2001.

Originally developed as a priority to interconnect portable equipment, such as computers, telephones, electronic agendas, associated peripherals, etc., this network is today intended to be used for all types of equipment included in a environment of reduced dimensions, such as for example audio-video devices, and household appliances.

Each of these pieces of equipment is fitted with radio frequency transceivers, which all use the same protocol, thus constituting a network, and thus allowing the exchange of information between the various pieces of equipment which are connected to it.

The connection to this network and the behavior of the transceivers included in it are defined and governed by the Bluetooth protocol.

This radio network operates on the 2.4 GHz frequency band, belonging to the so-called “ISM” (Industrial, Scientific and Medical) frequency bands, free of rights if the equipment meets certain characteristics.

The authorized bit rates depend on the operating mode, but are typically around 1 Mbit / s. In other words, Bluetooth is a specification describing a low-power, but high-speed radio transmission protocol. Some of the communicating radio equipment requires high speed information transfers, such as for example Internet or video links, links with printers, etc.

In practice, transferring broadband data over a network such as Bluetooth leads to relatively high hardware and consumption costs. Indeed, being located in a high frequency range, there is a fairly strong attenuation of the signal, inducing a limited range because in addition, the Bluetooth specification imposes power limits. It is therefore difficult, with a radio network conforming to such a standard, for example to read by telemetry the information stored at the level of a sensor of a tank in a garden a few tens of meters away.

In addition, a local network implementing this standard may prove to be too expensive, taking into account the electronic components imposed by the standard, for certain equipment having at its base a very low cost price.

One of the objects of the invention is therefore to solve these problems, within the framework of a local transmission network.

Another object of the invention lies in the establishment of a data transmission network in which part of the equipment does not require high speed communications, but imposes in return constraints on the consumption / performance balance.

These are typically devices which have little information to exchange (for example, heating regulation, meter or storage tank telemetry, etc.). These can then be satisfied with a much less expensive technology, the consumption of which is very greatly reduced. In doing so, it is then possible to implement self-supply, the service life of which can reach several years, thus making it possible to dispense with an external supply by sector.

Among the solutions proposed in the prior art, there are local wired networks. This type of network consists in connecting the communicating equipment by wire link. These are therefore generally fixed devices, which use a common communication protocol. To date, there is no single standard for this type of network, which can be adapted to any type of equipment. In addition, this type of network suffers from several drawbacks, which explains its poor success in domestic environments. Among these disadvantages, we can cite:

• the cost of the maintenance installation: the need to connect the equipment by wire makes the installation particularly expensive in existing constructions;

• lack of flexibility: for similar reasons, the addition of new equipment to the already installed network requires the passage of cables; depending on the placement of the equipment, significant constraints of cleanliness and aesthetics may appear;

• the lack of scalability: the connection of equipment in a wired network can only be done with fixed equipment. The constraints related to the repeated connection and disconnection of mobile equipment makes them unsuitable for this type of network.

Low-consumption wireless transmission equipment has also been developed for a number of targeted applications, integrated into fixed or mobile networks. Among these applications are mainly alarms and telemetry. There is no more standard in this type of network, each application sector referring to its own standards. In addition, the type of applications targeted often makes self-sustaining battery power and long-term compulsory. The technology implemented is therefore above all dictated by this consumption constraint.

This type of equipment operates in the aforementioned ISM bands, typically the 433 MHz and 868 MHz bands for Europe and 915 MHz for the United States. The bit rates used on this type of equipment are relatively low, and for equipment with a short service life, rarely exceed 9,600 bit / s in frequency modulation and 38,400 bit / s in amplitude modulation. The power authorized on this equipment varies according to the frequency bands used, typically between 10 and 500.

This type of equipment is always dedicated to a particular sector (alarm, telemetry, etc.) and the equipment is not compatible with each other, each sector having developed as already said its own standards. In addition, they have a major drawback arising from the fact that cost and consumption constraints make it necessary to limit the data transfer speed. The increase in flow rates induces either an increase in consumption or an increase in cost, or even both.

Finally, high speed wireless networks have been proposed, of the type corresponding to the Bluetooth standard. As already specified, this type of network is particularly suitable for the interconnection of multimedia electronic equipment. However, the constraints mainly linked to the speed used make this network unusable with equipment having an autonomous power supply over a long period (several years). In fact, when the envisaged application requires autonomous equipment, it cannot therefore be interconnected with this type of network. One of the problems resulting from this type of broadband wireless network lies less in the need to switch two separate networks than in the impossibility of having access to them with a single standard.

The objective of the present invention therefore aims to integrate into a Bluetooth type network, a network with consumption + speed + cost balance optimized by means of a wireless communication module, compatible with this broadband network, further respecting all definitions of its protocol.

In other words, the invention makes it possible to establish communications uniformly between equipment conforming to this protocol and very low consumption network equipment, making the latter appear as equipment of said broadband network, and accessible as such by any other equipment.

To this end, the communication module according to the invention, therefore intended to establish communications between the equipment of high speed and low power radio network, and equipment of a low consumption transmission network, comprises:

* a first interface with the high speed and low power network including:

• a so-called “front end” transceiver operating in the frequency band specific to the broadband radio network, typically 2.4 GHz;

• means capable of performing low-level baseband processing, and in particular intended to transform the data from the transceiver into information interpretable by the upper layers of the interface; • means able to carry out the processing related to the operating mode of the broadband network, that is to say processing specific to the broadband network, and more particularly to the Bluetooth protocol. In this regard, it should be recalled that the Bluetooth protocol breaks down on the one hand, into two layers called lower layers, necessarily implemented: L2CAP and

LMP, and on the other hand into a set of software layers, called upper layers, whose implementation is dependent on the application. The Bluetooth software layers are commercially available as source code (for example under the reference BOOST ^® Software by NewLogic society);

4 a second interface with the low-consumption data transmission network comprising:

• a front-end transceiver operating in the different frequency bands dedicated to low-consumption network equipment;

• means capable of performing low-level baseband processing, and in particular intended to transform the data from the transceiver into information interpretable by the upper layers of the interface; • means for managing the protocol or protocols used by said equipment; software for interfacing between the two aforementioned interfaces and intended to make the network equipment of low consumption appear as radio network equipment at high speed and low power.

The manner in which the invention can be implemented and the advantages which ensue therefrom will emerge more clearly from the example of embodiment which follows, given by way of indication and without limitation in support of the appended figures.

Figure 1 is a block diagram showing the architecture of said module according to the invention.

Figure 2 is a block diagram representative of the interface between the broadband radio network and the software layer of said module.

FIG. 3 is a block diagram representative of the interface between the low-speed, low-consumption network and the software layer of the module.

Figure 4 is a block diagram of an advantageous embodiment of the invention. Figure 5 is a schematic representation of a common front end circuit for the two interfaces.

Figure 6 is a schematic representation of the interfacing elements between the module according to the invention and low consumption equipment.

In the following description, the broadband network to which reference will be made is the Bluetooth network.

It is however understood that the communication module according to the invention is adaptable to any type of broadband radio network, not necessarily in accordance with said Bluetooth specification. In particular, it could be extended to all other standards or specifications for high speed wireless data transmission, presenting similar operating constraints in terms of cost + consumption + performance balance.

There is schematically shown in Figure 1 the Bluetooth broadband network by the reference (1) and the local network of very low consumption under the reference (2).

The objective of the module according to the invention is to allow a wireless data transmission network respecting the constraints of speed, consumption and cost necessary for certain applications, in this case the very low consumption network (2 ), to become compatible with a broadband radio network, in this case the Bluetooth network (1), not respecting said constraints.

To this end and fundamentally, the module according to the invention comprises three characteristic elements, namely first of all a Bluetooth interface - high speed and low power network interface (3), intended to reveal said low consumption network (2 ) as a fully-fledged Bluetooth device, and thus capable of being interconnected as such in said network (1).

More specifically, this Bluetooth interfacing (3) shown in more detail in FIG. 2, respects the conventional division of Bluetooth equipment and first of all comprises a transceiver (7), called “front end”, operating according to the band frequency of the Bluetooth network, and typically 2.4 GHz. Given the high operating frequency, this transceiver is made on a purely "hardware" circuit and does not incorporate software. This transceiver is associated with two upper layers (8) and (9), respectively: • a layer conventionally called the “MAC” layer (Medium Access Control), but generally referenced in Bluetooth terminology under the name “Bluetooth Link Controller” (8), intended, according to the Bluetooth Protocol, to perform low level band processing basic. Given its complexity and the necessary computing power, this layer is generally produced by signal processing processors or by programmable logic. The “Bluetooth Link Controller” is software managing the link layer of the Bluetooth equipment and whose functionalities are perfectly defined in said aforementioned Bluetooth specification; these features mainly consist of:

* in establishing the network connection; in the management of links and packet types;

* in the correction of errors; in low-level authentication mechanisms. • a software layer called "Bluetooth Link Manager" (9), intended to carry out processing linked to the Bluetooth operating mode. This layer is less complex, manage, it is in the form of software (such as, for example marketed under the reference BOOST ^® Software by NewLogic company) focused on different processors. The “Bluetooth Link Manager” is software interfacing with the “Bluetooth Link Controller”, and whose functionalities are also perfectly defined in the Bluetooth specification; these functionalities consist mainly: in the transmission and reception of data; in the identification of equipment; in establishing the connection; in the management of the equipment operating modes.

The Bluetooth specification defines other software devices that support higher level functions. However, only the “Bluetooth Link Controller” and “Bluetooth Link Manager” software are used in the module which is the subject of the present invention.

A second fundamental element of the module according to the invention resides in the interface with the local transmission network of low consumption data (2). This interface (5), shown in more detail in relation to FIG. 3, basically breaks down into three parts: a “front end” transceiver (11) operating in the different frequency bands dedicated to this type of equipment, and in particular the aforementioned free frequencies 433, 868, 915 MHz, and of course, any other band which could be released for this use. This transceiver formally corresponds to the physical layer of the interface (5). It is made in wired electronics only; a "base band" (12), intended to recover the data coming from the physical layer of the "front end" (11), and to extract therefrom the information usable for the upper layers. Typically, the physical layer provides data not directly representative of the information initially transmitted by the transceiver. Before it can be used, this information must be processed and formatted. This is the role of this layer, conventionally called the MAC layer (Medium Access Control). This layer can be produced by a signal processing processor or by programmable logic, and in practice performs the following functions: • demodulation;

• synchronization;

• error correction. a software part (13) ensuring the proper operating mode of the low consumption network. This operating mode, most often governed by specific protocols, can vary depending on the equipment installed in said network, and therefore only depends on the field or fields of application in which this module is used.

An original method of implementing the two Bluetooth (3) and low consumption (5) interfaces, proposed in accordance with the invention aims to minimize duplication of the "hardware" parts. In the layered description of the two interfaces, it appeared that certain parts could only be produced in hardware form, without recourse to software help. In the simplest implementation of the module according to the invention, these parts must be produced and installed separately, only the software layers being able to be combined within the same processor.

The module according to the invention consists in designing the low layers (physical and MAC) of the low power network in a manner very similar to the low layers (physical and MAC or Link Controller) of Bluetooth, making it possible to merge the Bluetooth and low interfaces. consumption. The following principles are therefore proposed for the implementation of the module (10): • The physical layers (the radio front end) are as close as possible. As the common realization in analog of blocks having different specifications is much more difficult than a digital realization, rarchitecture retained for the front-end, allows to digitally process the signal very upstream. The implantation of circuits in digital form in fact allows a higher level of integration and greater flexibility thanks to the use of digital signal processing techniques;

• The base band layers (MAC layers of the low-power network and Link Controller layer of Bluetooth) are very similar and implemented entirely in digital. The differences that remain between the two must be implemented differently, but in digital form, therefore much more integrated than in analog.

The solution proposed in FIGS. 4 and 5 for the common front end (11 and 7) therefore consists of an architecture called "low IF" consisting in mixing (translating) the incident radio frequency signal (14) into a low intermediate frequency, the order of a few hundred kHz. For this purpose, a local oscillator (15) operating at a frequency equal to f ^ = f _if is used, where f _rf is the frequency of the incident signal (14) and f _lf is the chosen intermediate frequency. Two mixers (16 and 17) are used. The mixer used in channel I (16) receives on the one hand the incident signal (14) and the local oscillator (15). The one used in the Q channel (17) receives on the one hand the incident signal (14) and the local oscillator (15) phase shifted by 90 ° by a phase shifter network (18). Two low-pass filters (19) filter unwanted signals from the mixer (“up-conversion” product). Two variable gain amplifiers (VGA) (20) are then used to amplify the signal to provide sufficient amplitude for the two analog-to-digital converters (ADC) (21).

The principle presented makes it possible to propose a minimal analog structure allowing to function either on the low consumption network or on Bluetooth. The only difference concerns the frequency of the local oscillator (15), when the two networks do not operate on the same frequency (for example: 2.4 GHz for Bluetooth and 868 MHz for the low power network). The two ADCs (21) supply two digital signals I and Q which are then processed by the common part of the base band (12 and 8). For this, the low consumption network uses the same principles as Bluetooth on all the characteristics which define the structure of the base band. These are mainly:

• the principles of synchronization between the transmitter and the receiver,

• the coding of the transmission channel,

• the principle of spread spectrum by frequency hopping,

• the principle of error detection and correction.

The grouping of front-ends and base bands within identical structures for Bluetooth and the low-consumption network makes it possible to simplify the structure of the module according to the invention, in accordance with FIG. 4. The two Bluetooth and low-consumption networks ( 1 and 2) interface with the same front end (31), which interfaces with the same base band (32).

The upper layers specific to Bluetooth (L2CAP, LMP, and subsequent layers), and specific to the low-power network cannot be implemented in a similar way. But in both cases, they are performed in software form and the duplication of codes specific to the two layers is not problematic for integration.

The third fundamental element of the module according to the invention consists of a software layer (4) ensuring communication between the Bluetooth interface (3) and the low consumption interface (5). This software layer is intended to make the equipment of the low consumption network (2) appear as equipment of the Bluetooth network (1) in its own right, although they are not physically connected to said Bluetooth network.

The devices of the low consumption network (2) are members of a Bluetooth piconet as slaves, while the master of the piconet is the module (10) of the invention. First of all, the elements of the low-consumption network (2) are typically members of the same Bluetooth piconet. To this end, it should be recalled that the Bluetooth network is built on the principle of the piconet, grouping up to eight active devices, only one of which is said to be “master”, and intended to ensure the synchronization of the elements. of said piconet. In the case described, the master of the piconet in question is the module (10), as already mentioned. It is recalled that the Bluetooth standard version 1.1 of February 22, 2001 defines usage models, each accompanied by a profile. A usage model defines an adaptation of the Bluetooth standard to a specific use conditioned by an application depending on the type of equipment to communicate with each other. A profile defines the protocols and functionalities supported by said usage model. Of all the functionalities provided by the Bluetooth standard at the LMP and L2CAP level, the profile will define which are necessary to meet the specified usage model.

By analogy with the present invention, the possibility of connecting with a low consumption network corresponds to the definition of a new usage model.

Thus the interface software layer (4), an element of the present invention, is defined as being the control layer which is located between the application and the layers of the Bluetooth protocol for the usage model relating to the communication with very low consumption network equipment.

This interface software layer (4) manages the flow of information between the module (10) and very low consumption equipment.

FIG. 6 describes the principle of the flow of exchanges between the module (10) and a very low consumption equipment (2).

The software layer (4) firstly performs the discovery procedure (22) of the equipment present in the low consumption network. The procedure for discovering low-consumption equipment being different, essentially in terms of timing, from that defined in Bluetooth, it takes into account the specificities of this equipment so that, from an application point of view, the data returned by the discovery procedure are consistent with those returned by the Bluetooth procedure called Service Discovery Procedure (SDP).

Secondly, the software layer (4) manages the connection phase (23) of the low-consumption equipment with the module (10). The application layer issues connection requests through messages from the LMP and L2CAP layers. The software layer (4) interprets these messages and adapts them to the specifics of low-consumption equipment. Thus from the application point of view, the connection phase conforms to a Bluetooth connection. Thirdly, the software layer (4) manages, once the module (10) is connected to the low-consumption equipment, the data exchanges (24). Typically, exchanges are defined by the usage model relating to low-consumption equipment. They break down into the transmission of a “read request” message sent by the module (10). This message is acknowledged by the low consumption equipment. After a period necessary for processing the request message, the low-consumption equipment returns to the module (10) a message containing the read data. This message is then acknowledged by the module (10). Since the response time of a low consumption equipment can reach several seconds, the software layer (4) will implement the HOLD mode defined in the Bluetooth standard at the LMP layer. From the application point of view, the data exchanged between the module (10) and the low-consumption equipment is presented as data originating from standard Bluetooth equipment.

In a fourth step, the software layer (4) manages the disconnection phase (25) of the low-consumption equipment with the module (10). The application layer issues logout requests through LMP and L2CAP layer messages. The software layer (4) interprets these messages and adapts them to the specifics of low-consumption equipment. Thus, from the application point of view, the disconnection phase conforms to a Bluetooth disconnection.

In summary, this software layer (4) is intended to make the equipment of the low consumption network (2) appear as equipment of the Bluetooth network (1) in its own right, although they are not physically connected to said Bluetooth network.

We therefore understand the value of the module (10) according to the invention, in so far as, as already said, it makes it possible to connect a local network of very low consumption with the Bluetooth network or equivalent.

Given the respective constraints of each of the networks, it thus becomes possible to make two different types of constraints coexist.

Claims

1 / Communication module intended for establishing communications between high speed and low power radio network equipment and equipment of a low consumption transmission network, characterized in that it comprises:

4 a first interface (3) with the high speed and low power network (1), comprising:

• a transceiver (7), also called a "front end" operating in the frequency band specific to the high speed radio network (1); • means capable of performing low-level baseband treatments

(8), and in particular intended to transform the data coming from transceiver into information interpretable by the upper layers of the interface (3);

• means capable of carrying out the processing related to the operating mode of the broadband network (9);

4 a second interface (5) with the low-consumption data transmission network (2) comprising:

• a transceiver (11), also known as a "front end", operating in the different frequency bands dedicated to equipment in the low-consumption network (2);

• means (12) capable of performing low-level baseband processing, and in particular intended to transform the data from the transceiver (11) into information interpretable by the upper layers of the interface (5); • means (13) capable of managing the protocol or protocols used by said equipment of the low-consumption network (2); 4 software (4) for interfacing between the two aforementioned interfaces (3, 5) and intended to display the equipment of the low-consumption network (2) as high-speed and low-power radio network equipment (1) .

2 / communication module according to claim 1, characterized in that the high speed and low power radio network (1) conforms to the Bluetooth standard.

3 / Communication module according to one of claims 1 and 2, characterized in that the means capable of performing low-level baseband processing (8) consist of software, intended in particular to provide the following functionalities: 4 establishing the network connection; 4 management of links and packet types; 4 correction of errors; 4 low-level authentication mechanisms.

4 / Communication module according to one of claims 1 to 3, characterized in that the means capable of carrying out the processing related to the operating mode of the broadband network (9) consist of software, intended in particular to provide the functionalities following: 4 transmission and reception of data; 4 identification of equipment; 4 establishing the connection; 4 management of equipment operating modes.

5 / Communication module according to one of claims 2 to 4, characterized in that the transceiver (7) of the first interface (3) operates in a frequency band equal to 2.4 GHz.

6 / Communication module according to one of claims 1 to 5, characterized in that the transceiver of the second interface (5) operates in frequency bands equal to 433, 868 or 915 MHz.

Communication module according to one of claims 1 to 6, characterized in that the software providing the interface (4) is able to communicate information to the first interface (3), so that:

• on the one hand, an equipment of a high speed and low power radio network (1) analyzes an equipment as being an equipment of a low consumption network (2);

• and secondly, the information from equipment in the low-consumption network (2) is used by equipment in a high-speed, low-power radio network (1).