ES2253080B1 - SYSTEM AND METHOD OF DATA TRANSMISSION BETWEEN A MOBILE UNIT AND A RECEIVING UNIT. - Google Patents

Abstract

The invention relates to a method and system for transmitting data between a mobile unit (1) and a receiving unit (2), through a network (3) associated with repeat nodes (31) that receive the data, in the form of packets, from the mobile unit and transmit them to the receiving unit (2), which is configured to discard packets that are received repeatedly, by controlling a unique identifier associated with each packet. For greater security in terms of coverage, the possibility of transmission can be completed via the repeat nodes with an alternative way of transmitting the data, for example, via GPRS.

Description

System and method of data transmission between a mobile unit and a receiving unit.

Field of the Invention

The invention is included in the field of Radio communications with a mobile entity.

Background of the invention

There are a large number of systems of communication between a mobile entity, for example, a vehicle, and a fixed entity, for example, a central coordinator of transport, a hospital, etc. In these areas the satellite radio communication, radio modem communication (more limited in scope) and, lately, communication by mobile telephony For data communication through Cellular mobile phone networks have been used both Short Message Services (SMS - "Short Message Service") such as sending data using packages based on GPRS ("General Packet Radio Service ", a data communication service in packet mode overlaid on network infrastructure GSM)

For example, in the department of Electrical and Computer Engineering of the University of Athens (Greece) a project [S. Pavlopoulos et al ., "A Mobile System For Emergency Health Care Provision via Telematics Support-Ambulance", Proceedings of the 1998 IEEE International Conference on Information Technologies Applications in Biomedicine pp 150-154, Washington USA] which refers to a transmission system of Electrocardiographic signals, blood pressure and other biomedical signals from an ambulance using the GSM mobile phone system. The given solution does not offer the possibility of using alternative means independent of the global systems that allow a better autonomy in situations of saturation of repeaters or short distances.

Another project is the one being carried out by the University of Maryland in Baltimore (USA) and the Hospital from Maryland [D. Gagliano, "Wireless ambulance telemedicine may lessen stroke morbidity ", Telemedicine Today, Volume 6 (1), p. 22. Feb. 1998]. This project consists in the use of cellular communications and local area network technology for study the potential use of real-time transmission of vital signs and images of the patient from inside the ambulance to the hospital. Specifically, 4 lines were used of mobile telephony for the transmission of images and biosignals of medical monitoring Here the problem of communications is also attacks through a massive use of mobile telephony, with total dependence on the public system and without offering other alternative solutions

EP-A-0877331 describes a totally private system (no use of services public) where the problem of data communications is addressed with a mobile unit, through a transmitter radio modem and another receiver, without the use of other means; whereby the problem within cities it is only resolved at short distances.

In most cases, it is used only a means for communications, for example, exclusively the mobile cellular telephony, for example, GPRS, communication via satellite, etc. Now this means that sometimes they are used means that involve higher costs than desirable (by For example, if a public cellular mobile phone network is used, they must pay the corresponding fees) or a coverage that sometimes it is insufficient (for example, in cases where  use short or medium range radiomodems, communications cannot be made when the distance between the transmitter and the receiver is excessive and / or there are important obstacles). Further, in certain applications (for example, in the telemonitoring of ambulances), it may be convenient to have a bandwidth and a guarantee of very high availability of the channel communication; sometimes, public cell phone networks don't offer this guarantee of bandwidth and availability of channel, something that can lead to problems and make quality Not suitable for many applications.

Description of the invention

A first aspect of the invention relates to a data communication system between at least one unit mobile (which may include, for example, a microcomputer or embedded microcontroller, a radio modem and, optionally, a GPRS terminal, UMTS (Universal Mobile Telecommunication System) or another similar system for communications when it is not achieved communicate via the radio modem) and at least one receiving unit. He system includes:

said mobile unit, provided with first means of communication (for example, integrated by a radio modem that operates under the general control of a microcomputer or microcontroller embedded) comprising means for transmitting data by radio, in form of packages, so that each package carries a unique identifier that distinguishes said package from other packages of data transmitted by said first means of communication; Y

said receiving unit comprising means of reception of data packets through a first network of data communication (for example, Internet or a network corporate, with which the receiving unit can be connected to via an Ethernet connection), said first communication network data may be associated with (for example, through connections Ethernet) a plurality of repeat nodes.

In addition, the system comprises the repetition nodes, provided with second communication means (including, for example, radio modems) configured to receive radio data packets of said first communication means, the repetition nodes being configured to resend the transmission packets. data received from said first communication means to the receiving unit, through said first communication network of
data.

In accordance with the invention the receiving unit understands:

- reading media configured to read the unique identifier of the received data packets;

- comparison means configured for compare the unique identifier read from a received package with the unique identifiers read from other packages received previously, said comparison means being configured to produce an indicative repetition result if the Unique identifier read from a received package matches the Unique identifier read from a received package previously;

the receiving unit being configured for, in response to said repetitive indicative result, discard the corresponding package so that they are discarded data packets received in duplicate due to a receipt of the same data packet by the second means of communication of more than one repeat node. The receiving unit may be configured to analyze, process or operate on the data in the packets of data not discarded but not about the data in the Discarded data packets.

In this way, a system is achieved easily implementable in which the mobile unit can communicate with repeat nodes, even with more than one node at the same time, something that simplifies the design of the nodes and increase the possibility that each package arrives, at least one once, to the receiving unit, which is the one that finally deals with discard packages that are received repeatedly (by duplicate, in triplicate, etc.).

The mobile unit may also comprise third parties media (for example, a GPRS terminal - "General Packet Radio Service "- or UMTS -" Universal Mobile Telecommunication System "- controlled by the microcomputer of the mobile unit) to send data to middle rooms of data communication (for example, a radio interface and associated subsystems of an operator's mobile phone network of mobile telephony, which supports GPRS and / or UMTS) that are part of a second data communication network (for example, the corresponding public mobile / cell phone network). In this case, the receiving unit may be configured to be able to receive data through said second data communication network  (for example, in an IP (Internet Protocol) address associated with the receiving unit).

The mobile unit can be configured to selectively operate:

- in a first mode of operation in which it sends data through said first means of communication for reception by said second means of communication; Y

- in a second mode of operation in which send data through said third-party media to its reception by said fourth means of communication.

In this way, and the mobile unit being configured for, in response to a start action of data transmission,

- first try to establish a transmission of data in said first mode of operation;

- in the case of not being able to transmit data in said first mode of operation, try to establish the transmission of data in said second mode of operation, a system is achieved with a greater guarantee of success in communications (since there are two alternative ways, for example, radio modem and GPRS / UMTS).

For better guarantee of success and reduction of costs, the mobile unit can be configured so that, a once the data transmission has started,

- if, while transmitting data in the first mode of operation, it is detected that the transmission of data in said first mode of operation fails, an attempt is made to establish the transmission of data in the second mode of operation;
Y

- if while transmitting data in the second mode of operation detects the possibility of transmitting data in The first mode of operation is changed from mode of operation to so that it stops transmitting data in the second mode of operation and data transmission is continued in the first mode of operation.

Normally, it may be convenient to use the more "proprietary" route (in this case, for example, the route that use the repeat nodes), which may be the safest and / or economical, and leave as a "backup" the second mode of operation (for example, GPRS, UMTS or other mode involving use from an external network that requires payment for transmissions).

The first media and second media can be media by radio modem (i.e. modem for data transmission equipped with a radio transmitter / receiver -transceptor- that allows transmitting and receive digital data via radio).

Third media can comprise a GPRS or UMTS terminal and the middle rooms of communication can comprise radio interfaces of a cellular network of telecommunications that supports GPRS or UMTS; in that case, the second data communication network may be part of said network telecommunications cell phone

The first data communication network can be the Internet or a corporate network.

The mobile unit may be equipped with a microcomputer configured to perform, in real time, the following functions:

request and receive information from a monitoring device (for example, from a device medical monitoring);

compress and encrypt such information;

send such information to the nodes of repetition, through a radio modem.

The microcomputer can consist of a microcontroller configured to operate with a stored program in a non-volatile memory, so that it does not require initialization from disk

The mobile unit may include a medical monitor of a patient and be configured to transmit, in the packets of data mentioned above, data collected by said monitor doctor.

Another aspect of the invention relates to a method of data communication between at least one mobile unit and a receiving unit, comprising the steps of:

transmit data from the mobile unit, by radio (for example, via radio modem), in the form of packages, of so that each package carries a unique identifier that distinguishes said packet of other data packets transmitted from the mobile unit;

receive packages (for example, via radiomodem), in at least one of a plurality of nodes of repetition, and forward the data packets received in said node or nodes to the receiving unit, through a first network data communication (for example, Internet or a network corporate) associated with said repetition nodes;

receive the packets in said receiving unit, through said first data communication network.

According to the invention, the method comprises The steps of, in the receiving unit:

read the unique identifier of the packages of data received;

compare the unique identifier read from a package received with the unique identifiers read from others packages received previously;

discard the received package if the Unique identifier read from said package matches the Unique identifier read from a previously received package.

In this way, data packets are discarded received in duplicate due to a receipt of the same package of data for more than one repeat node. In this way, in the receiving unit, the data can be analyzed / processed in the packets of data not discarded but not the data in the packets of discarded data.

In response to a start action of Data transmission from the mobile unit, you can try: first, establish a data transmission between the mobile unit and the repetition nodes (for example, via radio modem); and in the in case data cannot be transmitted to any node of repetition, try to transmit the data in an alternative way of communication with the receiving unit (for example, via GPRS, UMTS or mobile telephony).

The method may be especially suitable. to transmit a patient's medical data between a mobile unit (for example, an ambulance) and the receiving unit (which can being in, for example, a hospital).

Specifically, one of the possible applications of the system of the invention is focused on telemedicine. Some of the advantages offered by the system described are based on the increase in the coverage area of communications between a moving vehicle and a fixed node by receiving from multiple locations and connecting to an established network. The fact that by means of a medical monitor connected to the patient who is being transferred by ambulance, electrocardiographic information, and other vital parameters such as blood pressure, etc., can be received in the hospital, in addition to alarms if something goes wrong, allows monitoring of the transfer by doctors in the hospital and study of any event by specialists who can give orders to the ambulance staff (which usually consists of the driver and a nurse or similar) to start treatment already during the transfer, leading a clear benefit for the patient since it allows a rapid diagnosis and better care. The invention allows the implementation of a telemonitoring system with an affordable cost and therefore with a great advantage, since it solves the problems in the vicinity of cities, where repetition nodes can be located in corporate buildings, which are already networked, achieving good coverage regardless of saturated public repeaters, and also in the vicinity of the hospital the communication could be direct to the reception unit (or to a repeat node directly connected to the receiving unit and which can be located in the same hospital). Using radio bands in the frequencies of common use, it is not necessary to carry out projects or the administrative fee if the maximum powers of free use are not exceeded; the system, by allowing the jump of
Automatic frequency to find free channels, manages this possibility, allowing to share with other users a set of free-use channels, in addition to allowing the use of specific channels assigned to an installation.

Other applications can also benefit of this invention as the bus position control, garbage collection vehicles, taxis, etc.

Brief description of the drawings

Then it goes on to describe very brief a series of drawings that help to better understand the invention and that expressly relate to an embodiment of said invention presented as an illustrative example and not limiting it.

Figure 1 is a general system diagram of the invention, in accordance with a preferred embodiment of the invention.

Figure 2 is a schematic of the topology of the communications network according to said embodiment preferred.

Figure 3 is a unit diagram mobile.

Figure 4 is the architecture diagram of the radio modem.

Figure 5 is a flow chart of the operation of the application embedded in the microcontroller of The mobile unit.

Figure 6 is a diagram of the protocol followed by the mobile unit for the exchange of information and the selection of working radio frequencies.

Figure 7 is a diagram of a node of repetition.

Figure 8 is a flow chart of the Repeat node operation.

Figure 9 is a diagram of the protocol followed by the repetition node for the exchange of information and command management

Figure 10 is a unit diagram Receiver

Figure 11 is a flow chart of the operation of the receiving unit.

Figure 12 is a diagram of the protocol followed by the receiving unit to establish the connection e Exchange information with other units.

Figure 13 reflects, schematically, some of the functional elements of the receiving unit.

Description of a preferred embodiment of the invention

The preferred embodiment corresponds to a Real-time communications system between one or several moving vehicles and other or other fixed receiving stations of data and with the possibility of issuing orders and commands to Mobile units for configuration or performance.

Figure 1 reflects the basic structure of the system, with a mobile unit 1 that communicates with a unit Receiver 2 through two data communication networks, one first network 3 which can be the Internet or a corporate network and a second network 4 corresponding to a cellular telephone network (HPLMN - Home Public Land Mobile Network) that supports GPRS and / or UMTS.

To the first network 3 are connected, through Ethernet connections 33, a plurality of repeat nodes 31 that each comprises a radio modem 12 connected in a manner operational to a microcomputer 32 with an Ethernet connection. He microcomputer controls the radio modem so that it can be carried conduct a two-way data communication between the unit receiver 2 and mobile unit 1, through said radio modem 12; radio modem 12 and microcomputer 32 constitute the second media described above.

The mobile unit, meanwhile, includes a user interface or similar, for example, a medical monitor 15 which includes means of collecting data related to a patient; an embedded microcomputer 16 is connected to the medical monitor which, together with a radio modem 11 operatively connected to the microcomputer 16, constitutes the first means of communication described above. Moreover, the mobile unit also includes a GPRS or UMTS 13 terminal operatively connected to the microcomputer 16 so that the GPRS or UMTS terminal 13 and the microcomputer 16 together constitute the third means of communication described above. Through the GPRS terminal or UMTS 13, mobile unit 1 can communicate with the unit receiver 2 through a cellular telephone network 4 that supports GPRS or UMTS, through base stations 14 of said network (which they represent the fourth most described media above); through GPRS or UMTS, the data sent by the GPRS or UMTS 13 terminal in the form of packets, arrive at a IP address associated with the receiving unit and can be recovered 41 by said receiving unit 2.

Receiving unit 2 can be connected (a via an Ethernet connection 33a) directly to a node of repetition 31a with configuration analogous to that of the nodes of repetition 31, that is, comprising a radio modem 12a and a 32a microcomputer for communication with the mobile unit 1. In addition, the receiving unit 2 can be connected directly to a optional 12b radio modem via an RS232 / USB connection (Universal Serial Bus). Logically, the receiving unit includes the minus an interface 21 with users, for example, a PC with graphic interface The receiving unit may be connected to the First network 3 through an Ethernet connection.

In this way, you can get a wide coverage area in communications between the mobile unit and the receiving unit, by installing a series of units Repeat 31 radio / Ethernet, which allow reception of the signal emitted by radio modem 11 located in the vehicle / unit mobile from different locations and the retransmission of packets of information through a corporate network 3 or Internet to which the aforementioned repeat nodes are connected 31 and the receiving unit 2 that can receive the data packets of one or more repeat nodes 31, rescuing the packages and in the case of receiving the same package several times, due to the simultaneous coverage of more than one repeat node 31 (31a), capture the first one you receive without error. The repeat nodes they are installed in places or buildings of the highest possible height and that have connection to the desired corporate network 3 or to Internet. Through this technique and by private, autonomous and with low or medium power transmitters (less than 5 watts) is possible to achieve a coverage radius of tens of kilometers depending on the height on the ground of the antenna of the repeaters. To ensure greater coverage, especially in remote areas, the system incorporates a second alternative of wireless communications through the public system called GPRS or UMTS that uses repeaters or base stations 14 of mobile telephony; a decision-making system, embedded in the microcomputer 16 of the mobile unit, decides to activate the option more suitable at all times (preferably, using the nodes of repeat 31 as long as you can connect with at least one of them, and the GPRS or UMTS only when it is not possible or difficult -by For example, in the case of a large ratio of transmission errors - the communication with repeat nodes 31). In this way, it get a very suitable system for telemonitoring of ambulances, to control the position of a network of vehicles and in general for any vehicle or set of vehicles that contain a source of information that interests telemonitoring

Figure 2 schematically reflects the system configuration, with several mobile units 1 that They move through a territory to cover. The system comprises a plurality of repeat nodes 31 connected to first network 3 of data communication (in this case, for example, the Internet, although it can also be a corporate network) and two receiving units 2 connected to said first network 3. In addition, the base stations that support GPRS or UMTS 14 (and that are part of a cellular mobile phone network 4), connected, through said cellular mobile telephone network 4, to a central of the provider of GPRS / UMTS 4a which, in turn, is in communication with the first network 3, so that the receiving units 2 can access the data sent by mobile units in the IP address correspondent. As can be seen in Figure 2, the mobile units 1 can establish communication links with the receiving units 2 directly (through node 31a or the radio modem 12b, see figure 1), through the nodes of Repeat 31 or through a base station 14 that supports GPRS or UMTS, from a public cellular mobile phone network. This form, depending on the number and location of the nodes of repetition, you can, in each case, design a network that communications that depend, to a greater or lesser extent, on networks Mobile phone commercials.

Mobile unit 1 is responsible for extracting from a team (such as a medical monitor) the information that is necessary transmit from the vehicle, treat it conveniently and transmit it wirelessly to the nodes of Repeat / receiving unit.

The mobile unit is basically composed of the following elements (see figure 3):

Radio mode 11 comprising a radio transceiver 1101 for UHF (Ultra High Frequency) data 300-3000MHz) and a 1102 modem for radio controlled by microprocessor; GPRS or UMTS terminal 13; a microcomputer 16 or embedded microcontroller with 1601 ports, Ethernet interface 1602, ports 1606 RS232, RS485 or USB, a central unit of UCP 1603 process, flash memory 1604 and timer with Reset Guardian - "watchdog timer" (WDT) - 1605; a unit of autonomous power supply 17, global GPS positioning system (optional) 18; the source of information (in this case, the monitor doctor 15); and a real time clock 19.

The radio modem 11 is a device that allows establish a digital data radio link and is the element physical that supports the primary communications link semi-duplex via radio with repeating units 31. Figure 4 illustrates, in more detail, a possible configuration of the radio modem, constituted by the radio transceiver 1101 specific for data and a modem 1102 with their respective transmission connections 1103 and reception 1104. It is governed by a 1105 microcontroller -with 1105A RAM that buffer input / output - which performs radio control functions, Switch 1106 receive / transmit mode, control 1107 change channel acting on the PLL (Phase Loked Loop) of the radio, 1111 controls the power, acts as an interface formatter-deformer between the data that they want to transmit and the modem, performs correction functions direct error FEC (Forward Error Correction) and encryption primary information (the encryption used in the channel via radio to prevent outside elements from having access to information transmitted). The antenna 1108 may be of the flexible type miniaturized or roof for vehicle. Radio modem 11 is connected to microcomputer 16 through input connections 1109 (RS485) and output 1110 (RS232) of data.

The specific characteristics of a radio modem Suitable for this application can be:

-

Operating frequency: band UHF, data transmission subbands with general character: 418 to 420 MHz, 428 to 430 MHz, 440 to 442 MHz, 450 at 452 MHz, with 25 KHz pipeline and sub-band of common use (no license required for powers up to 10 mW) 433,075 to 433,350 MHz with 25 KHz pipeline, and 868 to 870 MHz subband; authorized frequencies by the National Table of Frequency Allocation in Spain (also compatible in Europe).

-

transmission power: the power It can be adjustable between 10 mW and 5 W.

-

Channeling: 12.5 KHz, 25 KHz, 50 KHz. or 100 KHz

-

frequency radio modulation with DC coupling and flat signal band modulator

-

deviation between +/- 2.5 KHz, +/- 5 KHz., +/- 10 KHz and +/- 20 KHz.

-

kind digital modulation: GMSK (Gaussian Minimum Shift Keying), or 4DFSK (4 level Direct Frequency Shift Keying)

-

transmission speed: 9600 bits / s for 12.5 KHz, 19200 bits / s for 25 KHz, 38400 pipes bits / s for 50 KHz and 76800 bits / s for 100 KHz.

-

sensitivity -105 dBm @BER <10 ^ - 6 at 9600 bits / s.

-

weather TX / RX switching <2 ms.

-

secure private key based encryption without increasing the size of the information and generated in time real.

-

direct error correction FEC.

The GPRS or UMTS terminal 13 (figure 3) is based on the public data transmission system via GPRS radio or UMTS, which uses the mobile phone repeater network to data transmission without calling and charging  by amount of information and not by connection time. GPRS can allow transmission speeds of the order of 64 Kbits / s, and UMTS noticeably greater than GPRS whereby GPRS or UMTS can be alternative communications systems when the signal from the mobile unit emitted by the radio modem is not received on any node Repeat 31 (or if received poorly, with a quality below of a certain threshold). Basically, the transmission via Alternative GPRS or UMTS can be activated automatically by order issued by microcomputer 16 or upon request of the receiving unit 2 by means of a command issued by this same via GPRS / UMTS, so it is convenient that the terminal GPRS / UMTS 13 is always activated on reception on the mobile unit 1. The channel for receiving the information issued by this means, on the side of the receiving unit 2, it is the public network of data transmission (Internet). Receiving unit 2 is enabled for communication of data packets with the Unit Mobile 1 in the GPRS or UMTS service provider and a contract with a provider of this service.

The microcomputer 16 consists of a embedded microcontroller, that is, in a microcontroller with the program stored in a non-volatile memory type ROM-Flash 1604 or similar, you don't need Initialize from disk.

The embedded microcomputer or microcontroller is the element in charge of extracting the information of the equipment that generates it (medical monitor 15) by means of question-answer or other processes and carrying out on said information a treatment destined to the selection of the desired information, formatting, compression, Encryption and packaging for wireless transmission, in addition to managing the commands to the radio modem for the control of the radio channel, power and presentation of messages in the mobile unit. The microcomputer (see Figure 3) consists of a card that incorporates a CPU (central processing unit) 1603, a flash-eprom memory 1604 that stores the control program in a non-volatile way, an internal RAM for data operations (not illustrated in figure 3), a timer 1605 guardian reset to prevent the system from blocking due to data errors, automatically restarting the system when necessary, a set of 1601 digital ports for connection to the outside and a set of standard interfaces of communications such as RS232, RS485 or USB for connection 1606 with radio modem 11, and Ethernet 1602 or USB interface for connection with the source of information (modern medical monitors 15 have an Ethernet interface). The microcomputer has been provided with a real time clock 19 to mark the packets with the time in which they are generated. The operation of this element is based on maintaining a dialogue with the information generator to establish its operation mode and request the necessary information; This information is stored in a temporary buffer and in a first step the information to be transmitted is distributed in other specific temporary buffers, one for each different variable. On said specific variable buffers a real-time compression process is carried out (real time is understood when the treatment time is much shorter than the generation of said information). The encryption technique used can be by Wawelet Transform ; With the specific predictor used in practical experiments, a compression of the order of 10: 1 has been achieved. Once the compression process has been carried out at a fixed length, the package to be sent is formed, with an identification header that includes the order number of the package, name of the mobile unit and date and time stamp, then the compressed graphic information and the exact number; The package ends with a byte obtained from. the overflow sum of the previous bytes called checksum and an end of packet identifier. Once the package is built, it is subjected to an encryption operation on the radio modem and is sent via radio to the repeater unit (see Figure 6). If GPRS or UMTS transmission is activated, in this case the packet encrypted by the embedded microcontroller is sent and sent to the GPRS / UMTS unit, adding in this case the destination IP address, that is, in this case the one associated to the receiving unit 2. Other functions of the embedded microcontroller is the control of the radio channel: since this system allows the existence of several mobile units connected to different radio channels in the repetition nodes 31, a protocol is established that establishes the channel of radio in use based on the reception of the connection confirmation with the corresponding reception node 31 (see Figure 6).

As discussed above, the unit mobile 1 incorporates an autonomous power unit 17 (figure 3) responsible for supplying the electric current necessary for the operation of the elements of the mobile unit. This unit of Autonomous power can consist of a set of batteries accumulators, of the type nickel-metal hydride, lithium-ion or gel lead, a set of high efficiency switched regulators (80%) to provide the voltage stabilized and protected against overcurrents at all elements. In addition, it can include a voltage monitor for the Autonomy time notice. Preferably allow connection to other sources of energy existing in the vehicle, such as the socket 12 Volt burner current, allowing the recharge of  accumulators with the vehicle engine running and the fully autonomous operation as in the case of entering an ambulance to a monitored patient from before arriving at the vehicle (in this case the radio modem antenna 11 can be short and  flexible and inside the vehicle can be changed to an antenna fixed roof vehicle or with magnetic fixing base).

The mobile unit can also include a System Global Positioning GPS 18 (figure 3); this optional item allows the transmission of the position of the mobile unit 1. The GPS system 18 is connected to microcomputer 16 to be able to be interrogated by this, so that they can be incorporated into each package the corresponding geographic coordinates with the mobile unit position 1. This option offers the possibility to estimate the time of arrival at the reception point, information important in case of transfer of patients by ambulance.

Figure 5 is a flow chart of the operation of the application embedded in the microcomputer 16 of the mobile unit, and reflects the following steps:

S51: it starts from the initial configuration of the team.

S52: data are requested from the medical monitor, by an S52a Ethernet communication with said monitor.

S53: with the data obtained, the packets of data to send.

S54: formatting is performed (the information of each variable in a different buffer) and change of resolution (the optimum resolution is assigned to each variable), apply a compression process on the graphic variables with fixed relationship, and the formation of the new package and encryption of it.

S55: via RS232 / USB communication, it It acts on radio mode 11 for sending packages.

S56: via RS232 / USB communication with the radiomodem 11 can also receive commands from the unit Receiver 2, for example.

Figure 6 is the protocol diagram followed by mobile unit 1 for the exchange of information and selection of working radio frequencies.

S61: Be part of a configuration of start.

S62: it is sent by radio modem 11, messages from connection in several frequencies, to establish connection with the minus a repeat node 31.

S63: reply from some node is expected repetition. If no repeat node answers, it passes (possibly, after several attempts) to step S64; if any Repeat node answers on an F1 frequency, goes to step S65

S64: the system considers that it is not possible establish communication with repeat nodes 31, so the data will be sent by GPRS or UMTS (using the terminal GPRS / UMTS 13).

S65: since a repeat node has answered, packets are sent to that node, in the channel corresponding to the frequency F1.

S66: after sending one or more packages, it wait for confirmation of receipt from the repeat node. If not There is confirmation, go to step S64 (for sending by GPRS or UMTS, to delay or further the transmission process). If there is confirmation of reception, it goes to step S7.

S67: Check for more data packets to send; if there are data packets left to send, it returns to step S65. Otherwise, go to step S68.

S68: END.

On the other hand, the repeat nodes are the entities in charge of receiving the packages issued via radio by the mobile unit 1 via radio modem 11 and forward them via the first network 3 to the receiving unit (or to the receiving units, since they can be several, see figure 2). They can also be placed more of a repeat node 31 in the same location, allowing more than one mobile unit has service for this system within the same coverage area, as well as the repeat nodes can be configured with a simple design, for communication with One mobile unit at a time.

Repeat nodes 31 can be designed to from elements similar to those of the mobile unit 1. Specifically, in a preferred embodiment of the invention, each repeat node 31 may comprise an embedded microcomputer 12 with 3201 Ethernet interface, for connection via Ethernet 33 to the 3 data communication network (Internet or corporate network), connected (RS232 / USB) 3202 to radio modem 12.

Radio modem 12 can have the same features and functionality of the mobile unit (it can comprise a radio transceiver for UHF 1201 data and a modem for 1202 radio controlled by microprocessor). The location of the radio modem can be a closet that also houses the microcomputer 32 and to the power supply unit (not illustrated in the Figure 7) and preferably located near the antenna outside 1203 in order that the antenna cable (type RG8 or similar) does not have a length greater than 20 meters, minimizing thus the cable attenuation. The outdoor antenna 1203 will be preferably a radio antenna for frequency bands in which the radio modem operates, the radiation pattern will be omnidirectional and the type of vertical collinear gain antenna of at least 6dBd. The antenna is preferably located in the most high roof of the building to get a larger area of coverage.

The microcomputer 32 may consist of a embedded microcontroller, analogous to that of the mobile unit, that is, with the same physical structure (UCP 3203, ports 3204, memory FLASH 3205 and RAM 3206, etc.) and differing from the microcomputer of the mobile unit merely in the stored program. The performance of the embedded microcomputer 32 of the repeat node 31 is based on the reception of the packets that arrive at radio modem 12 and via interface 3202 (RS232, RS485, etc.), of the radio modem to the embedded microcomputer 32 that analyzes them and once determined the integrity of each package, sends it through the Ethernet interface 33 to the IP addresses of the units 2 receivers, being able to use various protocols such as TCP / IP, UDP, AppleTalk or others.

In a preferred embodiment of the invention, in the start-up or after a reset of the microcomputer 32, are emitted interrogation messages to all IP addresses that are in a list with the possibility of tele-updating and that correspond to the receiving units 2 that are desired to receive the Mobile units information. The receiving units 2 that respond at that time are written in another list of units "active" receivers and from here the packages received via radio modem of mobile units are sent via Ethernet only to the addresses of the receiving units 2 listed as "active." Once the microcomputer 32, send orders to radio modem 12 to explore sequentially on all radio channels that you have enabled, repeatedly until you receive packages from a mobile unit 1. From that moment on, the process of retransmission of packets to Ethernet interface 33 destined for receiving units 2 active; if packages are no longer received due to lack of coverage, the system returns to the state of Channel scan until they are received again.

Figure 9 illustrates, schematically, this process. From a startup configuration (S90), the node of repeat sends (S91) an interrogation packet to all receiving units 2 included in a list of units receivers available to the repeat node. Some of said receiving units 2 answer, and the repeat node establishes (S92) a list of receiving units considered "active" and that includes the receiving units of which He has received a reply. In a next step (S93) it is explored, to via radio modem 12, sequentially all channels of radio you have enabled, repeatedly (S93a) until receive packages from a mobile unit 1. From that moment on the retransmission process begins, and packets are sent (S94) received to Ethernet interface 33, destined to the units Receivers 2. After sending a package, the system Check (S95) if there are any packages left to send and in the case Yes (S95a), repeat the step of sending a package, and so successively, until the system detects (S95) that there are no remaining packets to send, in which case return (S95b) to step S93 (channel scan).

It is possible to add a new receiving unit 2 "active" by sending from it a package that produces an interruption (S96) in the microcomputer process embedded 32, which receives and analyzes (S97) said package and adds (S98) the receiving unit in question to your list of receiving units "active", then return (S99) to continue their previous task

The embedded microcomputers 32 of the nodes Repeat 31 may have other auxiliary functions, aimed at teleconfiguration and quality management of communications, such as the activation or deactivation of the node repetition, update of the list of receiving units, reading the statistics of lost or checksum packets wrong, etc.

The power unit provides the voltage electrical operation to other equipment and may consist of a power supply with supply from the mains, a battery of lead gel accumulators (12 volts 7 amps hour) and a high efficiency switched regulator (0.8 or more) to supply a stabilized voltage, protected against overcurrents and with autonomy of several hours against cuts of the power grid

Figure 8 is a flow chart of the operation of the repeat node; in one step S81 is received information in radio modem 12 and, based on said information, the computer system tries to rebuild (S82) the packages sent by the mobile unit. Once a package has been rebuilt, it does an error control (S83) ("checksum" control); yes no error detected, the packet is sent (S84) to the unit Receiver 2, via Ethernet connection 33. If a error, packet (S85) is discarded (now, there is the possibility that the receiving unit receives the package from another repeat node 31).

On the other hand, the receiving unit 2 is the responsible for receiving the packets issued via the first network 3 of data communication, through repetition nodes 31, or to through the second data communication network 4, via GPRS or UMTS The packages once received, and through a process that discard multiple copies of the same package sent by different repeaters, are decrypted, decompressed graphic information, reordered, stored and presented to the operator.

Receiving unit 2 may be integrated by the following elements (see figure 10): Personal Computer (PC) 21 with display 21a and Ethernet interface 22 for access to the 3 network of computers (Internet, corporate network etc.); the PC can be equipped with an interactive application in graphic environment for communications protocol management, storage of the information and graphic presentation of it. A radio modem optional 12b allows additional functions such as reception direct from mobile unit 1, useful in cases such as receiving a patient on foot of ambulance and have the information of monitoring on a portable personal computer connected to the radio modem with a radius of action of hundreds of meters. Preferably, a personal computer with a graphic monitor and  current technologies 500 MHz CPU or higher RAM of at least 64 Mbytes, hard disk of at least several GBytes, RS232 interfaces and Ethernet, and Operating System in graphic mode.

In a preferred embodiment of the invention, the receiving unit 2 includes an interactive reception application and presentation made in a programming language that allows graphic presentation and object orientation, and that has the following functions:

- inform the repeat nodes of the entry into activity of this unit in the event that the computer was turned off before running the application;

- receive the generated information via Ethernet on mobile units destined for that receiving unit 2, through a process that includes the steps of: deciphering the information that makes up the package; identify in the header of pack your sequence number and unit of origin and check its integrity through the calculation and comparison of checksum;

- if the package is correct the information is decompress and distribute the information of each variable, graphic or numerical to a specific buffer for each one;

- then the information is presented in screen and, if the corresponding option is activated, stored in non volatile support.

Figure 11 schematically reflects this process:

In a first step, the information is received in radio modem 12b (S111) or from Ethernet 22 (S112). Be rebuild the packages (S3) and check / control is done of errors (checksum is controlled) (S4); if he "checksum" is incorrect, that is, if an error is detected, it discard the package (S115) and if no error is detected ("checksum correct"), we proceed to the graphic representation (S116) and optional recording (S117) of the information. In addition, there is the possibility of sending the information to other units receivers, via Ethernet (S118).

If more than one package with the same is received sequence number and with the same unit number of form correct, it is assumed the first to arrive discarding the rest for being copies of the first sent by other repeaters with coverage simultaneous at that time.

Figure 12 schematically reflects this process, starting from a connection startup configuration (S120):

S121: connection messages are sent to the IP address of all repeat nodes 31, so that these repeat nodes include receiving unit 2 in your list of active receiving units.

S122: is checked repeatedly (S122a) if packets of information arrive at the unit's IP address Receiver 2, until packet arrival is detected (S122b).

S123: it is checked if the received package has a sequence number (n + 1) corresponding to the sequence number (n) from the previous package, increased by one. If affirmative (S123a) is made (S124) a registration and presentation of the information, and return to step S122 to see if more arrive packages. In the negative case (S123b), that is, if the package detected does not correspond to the package that should follow the package above, it is checked (S125) if the package has a number of sequence equal to the previous package (or equal to any package previous received in the current packet transmission) and, in the If yes, the package (S126) is discarded (because it is assumed that it is a repetition, for example, due to reception of the packet for more than one repeat node 31). If the package does not has a sequence number equal to the previous package (or a any previous package) can be stored for use later, when the package that comes before it has arrived sequence set in the mobile unit.

The application may have auxiliary functions intended to present information on the quality of communications, to be able to study the state of the link so current and averaged, presentation of alarms or important events occurred in the mobile unit.

Figure 13 reflects how the receiving unit (2) includes:

- reading media (24) configured to read the unique identifier of the data packets received through of the Ethernet interface 22;

- comparison means (25) configured for compare the unique identifier read from a received package with the unique identifiers read from other packages received previously, said comparison means being configured to produce a result (26) indicative of repetition if the Unique identifier read from a received package matches the Unique identifier read from a received package previously;

the receiving unit (2) being configured for, in response to said repetitive indicative result, discard the corresponding package so that they are discarded data packets received in duplicate due to a receipt of the same data packet by the second means of communication others from a repeat node.

The radio modem element 12b of the unit Receiver can be identical to that of the mobile unit. Can be treated of an optional element, which is used in the case you need monitor with a portable receiver unit, that is, a portable personal computer, connected to the radio modem and with the interactive reception application installed.

The invention is implemented with a communications network topology with different technologies: private radio modem, GPRS / UMTS, Ethernet and different means of transmission (radio, cable), so it is a hybrid network. The network does not need to have its structure and number of nodes preset, but nodes can be created when a mobile unit 1 starts transmitting data, when a repeat node 31 is activated or when another receiving unit 1 is connected. This concept of Networks that are created spontaneously are now known as ad-hoc networks. The invention allows the use of an already established network, corporate or Internet, to forward the information emitted by a mobile node of limited scope and in the use of another layer superimposed with GPRS or UMTS technology to supplement the coverage in the remote areas of the repeating nodes The topology therefore does not correspond to any standard and could be defined as a wireless network with multiple point-multipoint structures with connection to a corporate network or the Internet. The concept of multiple point-multipoint structures appears when one or more mobile units connect simultaneously to several repeat nodes.

Throughout this description and claims the word "comprises" and variations of the same, as "understanding", do not intend to exclude other steps or components

Claims (19)

1. A data communication system between the at least one mobile unit (1) and at least one receiving unit (2), Understanding the system: said mobile unit (1), equipped with first communication means (11, 16) comprising means for transmit data by radio, in the form of packets, so that each package has a unique identifier that distinguishes said packet of other data packets transmitted by said first media; said receiving unit (2) comprising means for receiving data packets through a first network (3) of data communication associated with a plurality of nodes of repetition (31); said repetition nodes (31), provided with second media (12, 32) configured to receive radio data of said first means of communication (11, 16), the repeat nodes being configured to resend the packets of data received from said first means of communication to the receiving unit (2), through said first network (3) of data communication; characterized because The receiving unit (2) comprises: - reading media (24) configured to read the unique identifier of the received data packets; - comparison means (25) configured for compare the unique identifier read from a received package with the unique identifiers read from other packages received previously, said comparison means being configured to produce a result (26) indicative of repetition if the Unique identifier read from a received package matches the Unique identifier read from a received package previously; the receiving unit (2) being configured for, in response to said repetitive indicative result, discard the corresponding package so that they are discarded data packets received in duplicate due to a receipt of the same data packet by the second means of communication of more than one repeat node. 2. A system according to claim 1, characterized in that the mobile unit further comprises third communication means (13, 16) for sending data to fourth (14) data communication means that are part of a second network (4) of data communication, the receiving unit (2) being configured to be able to receive data through said second data communication network (4). 3. A system according to claim 2, characterized in that the mobile unit (1) is configured to selectively operate: - in a first mode of operation in which it sends data through said first means of communication (11) to its reception by said second means of communication (12); Y - in a second mode of operation in which send data through said third-party media (13) for reception by said fourth media (14), the mobile unit being configured for, as response to a data transmission start action, - first try to establish a transmission of data in said first mode of operation; - in the case of not being able to transmit data in said first mode of operation, try to establish the transmission of data in said second mode of operation. 4. A system according to claim 3, characterized in that the mobile unit (1) is configured so that, once data transmission has started, - if, while transmitting data in the first mode of operation, it is detected that the transmission of data in said first mode of operation fails, an attempt is made to establish the transmission of data in the second mode of operation;
Y - if while transmitting data in the second mode of operation detects the possibility of transmitting data in The first mode of operation is changed from mode of operation to so that it stops transmitting data in the second mode of operation and data transmission is continued in the first mode of operation. 5. A system according to any of the preceding claims, characterized in that the first communication means and the second communication means are radio modem communication means. A system according to claim 3 or 4, characterized in that the third communication means (13) comprise a GPRS terminal and the fourth communication means (14) comprise radio interfaces of a cellular telecommunications network that supports GPRS, and because the second data communication network (4) is part of said cellular telecommunications network. A system according to claim 3 or 4, characterized in that the third communication means (13) comprise a UMTS terminal and the fourth communication means (14) comprise radio interfaces of a cellular telecommunications network that supports UMTS, and because the second data communication network (4) is part of said cellular telecommunications network. 8. A system according to any of the preceding claims, characterized in that the first data communication network (3) is the Internet. 9. A system according to any one of claims 1-7, characterized in that the first data communication network (3) is a corporate network. 10. A system according to any of the preceding claims, characterized in that the mobile unit is provided with a microcomputer (16) configured to perform, in real time, the following functions: request and receive (S52, S52a) information from a monitoring device (15); compress and encrypt (S54) said information; send (S55) said information to the nodes for repetition (31), through a radio modem (11). A system according to claim 10, characterized in that the microcomputer 16 consists of a microcontroller configured to operate with a program stored in a non-volatile memory (1604), so that it does not require initialization from disk. 12. A system according to any of the preceding claims, characterized in that the mobile unit includes a medical monitor of a patient and is configured to transmit, in packets, data collected by said medical monitor. 13. A method of data communication between, at less, a mobile unit (1) and a receiving unit (2), Understanding the steps of: transmit data from the mobile unit, by radio, in the form of packages, so that each package carries a unique identifier that distinguishes said package from other packages of data transmitted by said first means of communication; receive packages, in at least one of one plurality of repeat nodes (31), and forward packets of data received to the receiving unit (2), through a first data communication network (3) associated with said nodes of repetition; receive the packets in said receiving unit (2), through said first communication network (3) of data; characterized because also includes the steps of, in the unit Receiver (2): read the unique identifier of the packages of data received; compare the unique identifier read from a package received with the unique identifiers read from others packages received previously, and produce a result repeat code if the unique identifier read from a package received matches the unique identifier read from a package received previously; in response to said result indicative of repetition, discard the corresponding package so that it discard data packets received in duplicate due to a reception of the same data packet by the second means of communication of more than one repeat node. 14. A method according to claim 13, characterized in that in response to an initiation action of data transmission from the mobile unit (1), an attempt is first made to establish a data transmission between the mobile unit and the repeat nodes, and in the event that it is not possible to transmit data to any repetition node (31), an attempt is made to transmit the data by an alternative means of communication with the receiving unit (2). 15. A method according to any of claims 13 and 14, characterized in that the communication between the mobile unit (1) and the repeat nodes is done by radio modem. 16. A method according to claim 14, characterized in that the alternative route of communication with the receiving unit (2) is via GPRS. 17. A method according to claim 14, characterized in that the alternative route of communication with the receiving unit (2) is via UMTS. 18. A method according to claim 14 characterized in that the alternative route of communication with the receiving station is by mobile telephony. 19. A method according to any of the claims 13-17, for transmitting data doctors of a patient between a mobile unit (1) and the unit receiver (2).