MXPA98006276A - Use of energy bursts for wireless networks - Google Patents

Abstract

A method and apparatus for communicating control signals via short energy bursts during a predetermined time interval. This method and apparatus is particularly well suited for wireless communication networks wherein the time intervals are assigned to each station on the network, and the presence of energy in that time interval signals a control signal to or from that station.

Description

USE OF SUDDEN ENERGY INCREMENTS FOR WIRELESS NETWORKS BACKGROUND OF THE INVENTION 1. Field of the invention This invention relates generally to communication networks and protocols, with particular relevance to wireless networks, or other networks that require a minimum signal inversion time. 2. Discussion of the Related Art Currently communication networks are formed by devices interconnected by wires or cables, and each having devices that conform to a protocol to send messages along those wires and cables. In some cases, a portion of such a network can be implemented as a wireless connection, using radio frequency or infrared signals between nodes. Such wireless connections are point-to-point, and have a single communications device at each end, each tuned to each other at a frequency different from the other devices in the same geographical area. A wireless network, on the other hand, is formed without physical connections between the devices, using, for example, radio frequency signals. Each device in the network is tuned to the same frequency, and each The device conforms to a protocol for sending messages to this common frequency. The protocol can allow communication between all the devices in the network or the protocol can restrict each device to communicate 5 only with a master device. Wireless networks offer a significant logistical advantage over wired networks, obviating the need to run wires or cables to each device. ^ B - »- ^ With the increasing availability of technologies of multiple media, and the growing demand for access to information, the potential market for residences or businesses based on Local Area Networks (RAL) is growing. The ease of installation and expansion of a wireless network allows a high demand for wireless RALs to be created. By For example, a central base station can provide wireless services, including voice, video and data to all communications devices in a home, or a wireless base station can provide communication between all the laptops in an office, or all computers on a campus. To be successful, however, the techniques and protocols used in these wireless networks must not be significantly inferior to their equivalent wired networks. Over the past decades, they have been developed protocols to effectively and efficiently manage the transfer of information within networks of communication equipment. An underlying premise in the development of these network protocols has been the network of a wired network infrastructure. In a wireless network, the assumptions on which the wired network protocols were developed may no longer be valid. Although most of the existing protocols are functionally extensible to wireless networks, their effectiveness and efficiency can be adversely affected by the lack of a direct connection between devices. A common protocol used for data communications in a wired network is a collective conductor structure with a "transmission" protocol. The devices on the collective driver, check the collective driver, wait for a period of silence, and then transmit. Collisions occur when a second device, which has also waited for a period of silence, begins to transmit simultaneously. The transmission protocol typically calls the devices to cease transmission in the event of a collision, and they try again in the next period of silence. Repeated collisions are avoided by causing each of the devices to randomly change their response time from the beginning of the silent period, so that they no longer respond simultaneously. This protocol Transmission, as the name implies, has its roots in radio transmission, and is still widely used for wireless voice networks, such as BC (Civil Band) radios. The transmission protocol, however, is not useful for high-speed data communications in a wireless network because collision detection in a wireless network is time consuming. In a wired network, the protocol typically calls for an active assertion of a logical level, but passive affirmation (ie a absence of affirmation of the active level) of the other level. Collisions are detectable in the transmitter by checking the collective conductor during the transmission of a passive level. If an active level is detected during this transmission of a passive level of the transmitter, this necessarily implies a collision. The wire transmitter • * - can automatically retransmit the message in the next period of silence. A device that transmits on a wireless network, however, is unable to detect if another device is transmitting at the same time. He The transmitting device, if it verifies the transmission frequency, will only detect its own transmission, since its power level will be significantly higher than that of a remote transmitter. The intended recipient, however, is remote from both transmitters, 125 typically receiving an unintelligible message caused by the # > simultaneous transmission by two transmitters at the same frequency. Because collisions are likely to occur, and the transmitter has no means to detect such collisions, the wireless transmission protocol 5 typically requires that the intended recipient recognize (REC) the receipt of each message. If he does not receive the message, or receives an unintelligible message, does not transmit the acknowledgment, or transmits an unrecognized signal (NREC).

"I the transmitter does not receive an acknowledgment, retransmits previous message. The requirement of a receiver recognition for each message in a wireless network has a composite adverse effect, because the transmission of each acknowledgment can also cause collisions. When traffic density increases, the probability of The collision increases exponentially due to the increase in reconnaissance traffic, as well as repeated transmissions with each collision. The interrogation network protocols, where a master device interrogates each of the others devices for messages, are applicable to wireless networks. Such protocols, however, are inherently inefficient for networks with non-uniform traffic patterns. During the interrogation process, each device in the network is interrogated, and the interrogation of the inactive devices consumes time. most of the interrogation protocols allow the suspension of interrogation of a device after some period of inactivity, to save time, but such protocols must also include means for the interrogated device not to notify the master device when it is activated again. Often this reactivation notification is achieved by providing an auxiliary connection to the master device, for example an interrupt line common to all devices. The equivalent of an auxiliary connection additional to a wired network, is an additional auxiliary frequency in a wireless network. Alternatively, an additional period of time may be set in each message period for a notification signal. The occurrence of a reactivation notification in this common line, or during the notification period, causes the master device to interrogate all the devices in the network again to determine which devices are currently active. In this way, it seems that the transformation of a wired network protocol to a wireless network protocol typically requires additional time, or frequency, or both. This additional demand of time or frequency is for the transfer of control information for the management of the wireless network. The purpose of this invention is to minimize the time required for communicate such control information within a network. Although the presented invention is particularly applicable to wireless networks, the embodied principles are equally applicable to minimize the time required to transfer control information from a wired network as well.

BRIEF DESCRIPTION OF THE INVENTION Essentially, the invention describes a method for transmit control information that has small sudden power increases within a wireless network protocol. The invention is best appreciated by noting that the control information in a network typically comprises short messages within a minimum information, although important. That is, the control information is typically that which, in a wired network, can be implemented in a single wire having one of two states. For example, a line of ^ Request for Send "on a wired network for a device to notify the master device that it has information to send. * A line of * Clean to Send" can be provided to notify the device that the transmission can start, or, the same line of * Request Shipping "could be used by the master device to signal this message from "Clean to Send" in a subsequent period of time. Similarly, a "Recognition" line could also be provided. In each case, the content of the information comprises a single bit of information: whether or not the device has something to send; whether the message was received, or not received; etc. Contrary to this single bit control information content, it is expected that the content of the data communicated in a wireless network will contain significantly more information. The use of the same protocol for both data and control is inefficient in one or the other of the protocols, or both. This invention provides very efficient and effective means for communicating control information messages (of a single bit within a wireless network without limiting or 5 necessarily affecting the protocol used for the effective transfer of data.) These efficient and effective means of communication are affected by the synchronization of all devices to a master device, and the allocation of a small 0 unit of time, in relation to the period of synchronization, to each device The presence or absence of power in the frequency of the network during each time assigned to the device, will mean the status of a bit of control information for that device. Depending on the function of the 5 bit of control, the presence of energy in the range of Assigned time can be confirmed either by the master device or each of the other devices. As an extension of this basic design, multiple control bits can be accommodated by multiple time assignments, as required.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a network of wireless devices. Figure 2 shows a timing diagram for receiving or transmitting control bits according to this invention. Figure 3 shows a circuit diagram for 'receiving and transmitting control bits according to this invention. Figure 4 shows a timing diagram for receiving and transmitting control bits and messages at the same frequency, or wire, according to this invention. Figure 5 shows a synchronization diagram 0 for communicating multiple messages to the same frequency, or wire, according to this invention.

Detailed description of the preferred embodiments of the invention. Figure 1 shows a wireless network, comprised of mobile stations 101 to 105, and a base station 110. For ease of understanding, a frequency is shown to send information to the base station, Fl, and a frequency to receive information from the station base, F2, although alternative modalities will further describe the use of the same frequency for both transmission 0 and reception. The equipment of the mobile station can either be discrete, or be incorporated directly into the destination device, such as a telephone. Each mobile station in this network is assigned an address. By simplicity, address 1 was assigned to mobile station 5 101, address 2 to station 102, etc. The address assignment can be established either by testing switches on each device, or by communicating messages which instruct the device to change its internal address. Also, additional devices can be added to the network, 0 or existing devices deleted, through the use of those addresses assigning and changing messages. The techniques for initializing such an address are commonly known and are not presented here. Because each mobile station will be transmitting at the same frequency to the base station, it must establish a protocol to handle communications in this network. Figure 2 shows a protocol for transmitting to a base station in a wireless network according to this invention. In the first time period 250, the base station 100 will transmit a synchronization pattern, which will be used by each station to establish a common time reference 200. The second time period 260 is subdivided into subintervals of time 201 to 205. Those time slots are assigned to each mobile station 101 to 105, corresponding to their addresses 1 to 5.

These time intervals are, for efficiency, of very short duration, and each has a fixed relation to the time 200 i established by the master station. If a mobile station 5 has a message to transmit to the base station, it will transmit a sudden increase in energy to the frequency of the network during its allocated time interval. That is, if the mobile station 103 has information to transmit, it will transmit a sudden increase in energy 0 during the time slot 203, and inform the base station, that the mobile station with the address 3 has information to send. During the 270 time period, the data transfer can be made, using the protocol established for the best data transfer, regardless of - this signaling protocol for sudden power surges. This particular mode is particularly well suited for a network with a relative hierarchy of 5 mobile stations, where messages from address 1 have priority over messages from address 2, messages from address 2 have priority over messages from address 2. address 3, etc. In such a network, the protocol may require that a mobile station does not transmit a sudden increase in energy if a sudden increase in energy is detected preceding its assigned time interval. That is, if address 2 sends a sudden increase in energy, addresses 3 through 5 are not (It would allow a sudden increase in energy to be used.

If this is done, the possibility of collision is eliminated, and the station sending the sudden increase in energy could be free to send its data in the immediately following time period 270. The receiving base station could know that the data coming from the address correspond to the time interval of the sudden increase in energy detected. The same protocol could be used by the base station to transmit information to mobile stations. The base station 110 will transmit a pattern of synchronization to mobile stations, on the frequency assigned to receive information from the base station, during the time period 250. During the time period 260, the base station will transmit a sudden increase in energy during the time interval assigned to the station intended to receive the message. The mobile station corresponding to the time interval in which the sudden increase in energy occurred could thus be altered to receive the subsequent data transmitted by the base station during the time period 270. Note also that this protocol is particularly very suitable for the messages intended for more than one mobile station. A sudden increase in energy may be transmitted for each of the intended stations during period 260, so that each is alerted to receive the subsequent data transmitted during period 270. This protocol is similar in concept to the protocols that include the addresses of origin and / or destination within the message data, but offers significant advantages through the use of sudden power surges, as described here. A sudden increase in energy, as the name implies, is a small sudden increase in energy transmitted to the assigned radio frequency. Contrary to the data signal, this sudden increase in energy has a criterion that is very satisfying To easily. There are digital devices that are very suitable for accurate time measurements, particularly with reference to a periodically confirmed synchronization pattern. In this way, the specification of time as a relevant criterion, rather than as a content, allows a solution at a very low cost. Instead of specifying criteria related to content, as must be done for data signals, the critical specification is simply when the signal occurs, and not its content. Figure 3 shows a device for the reception or transmission of control information through the use of specific energy surges, in accordance with this invention. In Figure 3a, the energy pulsed i detector 302 is shown separately from the demodulator of data 301, which amplifies the fact that the detection of sudden increases in energy does not require signal processing typically applied for data reception. The receiver 300 receives a signal from, for example, a base station 110, a generator of Synchronization 303 provides means for detecting synchronization signal 250 and establishing time reference 200 of Figure 2. Synchronization generator 303 produces a pulse at reference time 200. 350. This reference signal resets the SR latch ( Signal of Reference) 313, and also introduces 310 delay elements and 311. The delay elements 310 produce a pulse 380 after a predetermined time from the reception of the pulse in the reference signal 350. The predetermined time is determined by the address assigned to each device, so that it corresponds, in time, at one of time intervals 201 to 205 shown in Fig. 2. This pulse 380 is fed to gate Y 312. Also the feed to gate Y 312 is the output of detector 302. If a pulse of energy during period assigned to this device, according to what is indicated by pulse 380, the output of gate Y 312 fixes the lock of SR 313. Through the establishment of specific time intervals for each device < directed, the output of the bolt of SR 313, corresponds to therefore to the detection of a control signal of the intended base station for this device. In this exemplary embodiment, the detection of this control signal informs the device that the subsequent message of the base station 100 intends to be for this device. The delay element 311 generates a signal 381 after a predetermined time from the reception of the pulse in the Reference 350. This signal 381 is confirmed by the duration of the time period of the message 270, Gate Y 31.4 activates in this way to gate 315 during the time period of message 270 if and only if the Bolt of the SR has been placed, as described above, by the receipt of a sudden increase in energy during the allotted time period. Figure 3b shows a control device for generating a sudden increase in energy from a remote transmitter according to this invention. Points having the same function as described in Figure 3a have the same reference numbers. As presented above, the reference signal 350 will contain a pulse at a reference time 200 set by the base station transmission of a synchronization signal 250. The lock of the SR 313 will be reset by the occurrence of a pulse in the reference signal i 350. The delay element 310 will produce an impulse for 5 the time interval assigned to the device, one from 201 to 205. Figure 3b contains an additional latch 330. This latch 330 is used to signal the occurrence of a sudden increase in energy before the time allotted for this device. The bolt 330 is fixed or set 0 by the reference signal 350. If an energy pulse is detected by the detector 302, the bolt 330 is readjusted. In this way, at the moment of the pulse 380, the output of the bolt 330 will be confirmed if and only if no sudden increases in energy have been detected since the bolt was fixed or placed by the reference pulse. Momentum ? ^ of the time slot 380, the output of the latch 330, and a control signal 382 are fed to the gate Y 312. The gate Y 312 will lock the latch 313 during the time period 380 only if the bolt 330 is being installed, 5 noting that no other transmitter sent a sudden increase in energy before time 380, and control signal 382 is confirmed. The output of gate Y 312 is also provided to transmitter 337 as signal 385. After receipt of a confirmed signal 385, transmitter 337 will be activated, thereby sending a sudden increase in energy. The detector 302 will subsequently detect this sudden increase, which will cause the latch 330 to reset, which causes the gate Y to not confirm the signal 385, thereby ending the transmission of the sudden increase in energy. Alternatively, if the receiver 300 is deactivated during transmission, the signal 385 will not be confirmed at the pulse end of the synchronization interval 380. In this exemplary embodiment, the control signal 382 is confirmed regardless of the device having a message to be transmitted, and the transmission of this message is effected after sending the sudden power surge described above. The messages are placed in a waiting queue in the transmission separator 335. After the reception of a message, the separator 335 confirms the signal of control 382. This control signal 382 produces the generation of a sudden increase in energy during the period of time assigned to this device, as described above. Activation of the transmission of the sudden increase in energy also sets the latch 313, the output of which is fed to the gate Y 314. The delay element 311 confirms a signal 381 during the period of t message 270. If the Lock 313 is placed during this W 'f period, gate Y 314 confirms an activation signal for the gate 336, which carries out the transmission of the content of the transmission spacer 335. If there are no additional messages in a queue, the transmission spacer 335 does not confirm the control signal 382, . thus inhibiting the subsequent transmission of a sudden increase in energy. The exemplary embodiments of Figure 3 demonstrate the use of power increments to receive and transmit control signals which subsequently control the reception and transmission of messages. Could The same, or a similar logic is used to receive or transmit sudden increases of energy at the appropriate time intervals corresponding to other control signals as well. Also, the common elements of Figures 3a and 3b can be combined, and the modality , 25 shown could be implemented and executed by a program of computation, or a combination of equipment and programs, and computer systems, as would be apparent to one skilled in the art. Note that the transmission and reception of a sudden increase in energy can be made based on data equalization techniques normally used for reliable, error-free data transmission. Automatic gain control, pre and post signal conditioning, error correction and other techniques required to reliably determine which of two or more values have been received during data transmission, are not required to determine whether or not a sudden increase in energy occurred at a particular time. The mode presented in this way requires a separate transmission and reception frequency in relation to the base station, as well as the generation of a synchronization pattern by the base station, and synchronization to the mobile stations, at each of those frequencies. The figure 4 shows a protocol, which eliminates this redundant process. As shown, in the time period 450, the base station transmits a synchronization pattern, at the frequency used for both transmission and reception. This synchronization pattern establishes a time reference 400. The time period 460, contains time intervals 461 to 465, corresponding to addresses 1 to 5 of the mobile stations. During the time period 460, the station transmits one or more sudden power surges during the time interval corresponding to the intended receiving mobile stations. The reception of a sudden increase of energy during the assigned time interval alerts the corresponding mobile station to receive the subsequent data transmitted by the base station during the time period 470. The time period 480 is also divided into periods. times 481 to 485, corresponding to addresses 1 to 5 of the mobile station. If a mobile station has data to transmit, < transmits a sudden increase in energy during its allocated time slot, in relation to time reference 400. As described above, the protocol for transmitting to the base station could dictate that a mobile station does not transmit a sudden increase in energy, if it detects a sudden increase in energy at 0 time intervals before its assigned interval. The mobile station transmitting the sudden increase in energy could then subsequently transmit its data during the time period 490. The above modalities demonstrate the use of 5 transmissions of sudden power surges for predominantly one-way communications. That is to say, that within the time intervals described above, a remote station transmits data to the base station, and, except in the case of multiple addresses for the same message, the base station transmits data to a remote station. In such protocols, there is a period of sudden increase of energy per message, and, in a network with heavy traffic, such a protocol can be inefficient. Figure 5 shows one embodiment of the invention or objective, particularly very suitable for networks with continuously heavy traffic patterns. In this modality, the periods 570 and 590 after the periods of sudden power increase 560 and 580 contain a variable t number of message transfer periods. For example, if the base station has messages for three remote stations, three periods of message transfer could follow the period of sudden power increase of the base stations. The base station could confirm the sudden increase in power in the 0 time periods assigned to each of the remote stations, and transmit the messages in the same order as the confirmed sudden power surges. Figure 5 shows, for example, that remote stations 2, 3 and 5 have messages that are being sent from the base station, according to what was indicated by the sudden increases in energy in the time periods 502, 503 and 505. Messages from the remote station 2 will be transmitted first, in the message transfer period 571; then the message from the remote station 3, in the message transfer period 572, followed by the message from the remote station 5, in the period 573. Each remote station will notice if its allocated time period contains a sudden increase in energy, and also how many surges of energy, for other remote stations, have preceded their sudden increases. In the example given, station 2 will notice that it received the first sudden increase, and therefore will know that its message will be the first message from the base station. Similarly, station 3 could notice 4 that received the second sudden increase, and in consequence your message is the second message. Station 5 could similarly determine that your message is the third message. All stations in this mode will notice how many messages are being transmitted, noting how many surges of energy are transmitted in the period 560. In this way, the stations will know when the period 580 begins, in relation to the time reference 500. In this mode, remote stations are prohibited from confirming a sudden increase in power when another remote station has also confirmed a sudden increase in energy. If two remote stations have messages to send to the base station, two periods of message transfer will follow the period of sudden increase in power of the remote station. Each remote station having a message to send confirms a sudden increase in power during its allocated time slot in time period 580. Each remote station also notes how many other remote stations have transmitted a sudden increase in power before them. If a particular station is the first station to transmit a sudden increase in energy, it sends its message in the first message interval 291 of period 290. If another remote station notes that a sudden increase in energy has preceded its sudden increase of energy, it sends its message in the second message interval 292. In Figure 5, stations 1 and 3 are shown that have confirmed sudden power surges in time intervals 581 and 583. Station 1 transmits its message in the first time slot of messages 591. Station 3 has noticed that a sudden power surge 581 has preceded its sudden power surge 583, transmits its message in the second message time slot 592. The base station, knowing Since remote stations only have two messages to send, you can immediately start the process again, of synchronization for the next set of messages. Note, that if there are no messages from the remote stations, the time period of the sudden power surge 580 will not contain any sudden increase in energy and the synchronization sequence 550 may begin immediately after the sudden power surge period 580. Likewise, if the base station has no messages to send, the sudden power surge period 580 can begin immediately after the sudden power surge period 560. It is evident in these embodiments that the message transfer protocol format is independent of the protocol of sudden increments synchronization. energy. This invention is not limited to the transfer protocols presented here. For greater reliability, for example, explicit addressing could be included within each message. The use of sudden power increases in this protocol could serve the purpose of avoid collisions, assigning the message transfer time according to the occurrence of the sudden increases in energy, but it could not depend exclusively on the determination of the addresses. Similarly, the protocol of sudden increase synchronization of energy could be employed in a network without a base station explicit Each station could listen to all the messages transmitted, and select those messages that contain their assigned address, either as an explicit address, or determined by the time interval of the sudden increase of energy. The power surge synchronization protocol could be established by having a station transmit the synchronization signal as in a distributed synchronization network, * where the synchronization signal is transmitted by any station that initiates communication. It is evident that the use of the described energy surge synchronization protocol is not limited to its use as a signal of * "send request" as previously presented. synchronization of sudden power surges could be employed to signal other events as well. For example, an intervention period could be inserted between the aforementioned "sudden request power increase" period and the transfer period of the message. In this intervention period, the intended recipients could use surges of energy to signal a clean-up signal to send "corresponding." It is also evident that the use of a protocol synchronization of sudden power surges as HE ^ * '- describe here, is not limited to networks or to wireless networks in particular. In point-to-point communication systems, where the possibility of collisions does not exist, sudden increases in energy can be used exclusively for recognitions. In a wired network, the periods of sudden increases in energy can be used to eliminate the signaling wires, adding one or more " periods of sudden increases in energy to the wire that ^ r transfers messages. 10 Although the main application of the protocol 1 synchronization of power surges according to this invention is for single bit information, signals such as yes / no, can also be accommodated . Multiple bit information. The protocol can call a priority signal, wherein the transmitter assigns a priority, for example, from 1 to 3, for each message. Two periods of time per remote station could be assigned in the period of sudden power increase, and two bits could be transmitted as follows: 00 for a no message, 01 for a Priority 1 message, 10 for a message from Priority 2, 11 for a Priority 3 message. The foregoing merely illustrates the principles of the invention. Thus, it should be appreciated that those skilled in the art will be able to devise several arrangements, which, although not described or displayed explicitly here, they incorporate the principles of invention and thus are within their spirit and scope. %

Claims (11)

1. CHAPTER CLAIMEDICATORÍO Having described the invention, it is considered as a novelty and, therefore, property is claimed as contained in the following CLAIMS: 1. A method for communicating a set of control signals between communication devices that 10 operate in a network, where each of the control signals within such set is associated with each of the communication devices, the control signals each have a first and second state, the method characterized in that it comprises the steps of: 15 assigning, in relation to a time reference, time intervals associated with each of the communication devices; transmitting, via the first such communication device, a synchronization signal to all the others 20 communication devices on the network; receiving, by means of each of the other communication devices in such network, the synchronization signal of the first communication device; determining, by means of such transmission and reception of the synchronization signal, the time reference; and, transmitting, by means of one of the communication devices, a sudden increase in energy during the period of time associated with each of the devices, if and only if the control signal associated with each device is in a first state . The method according to claim 0 1, characterized in that it further comprises the steps of: transmitting a message to the communications device associated with the time interval within which the sudden increase in energy was transmitted. * 3. A base station for communicating a set 5 of control signals to communication devices operating in a network, wherein each of the control signals within the set is associated with each of the communication devices, the signals Each control has a first and second states, or the base station comprises: means for transmitting a synchronization signal to all communication devices on the network, the synchronization signal that establishes a time reference common to all the devices of communication in such 5 network, means for delineating, in relation to the time reference, time intervals associated with each of the communication devices, means for transmitting a sudden increase in 5 energy during the time interval associated with each of the communication devices depending on whether the control signal associated with each communication device is in the first state. 4. The base station according to claim 10, characterized in that it also comprises means for detecting a second sudden increase in energy of each of the communication devices. 5. The base station according to claim 4, characterized in that it also comprises 15 means for receiving a message from each communication device depending on the detection of the second sudden increase in energy. 6. A remote station to receive a control signal from a base station operating in a network, where 20 the control signal is associated with the remote station and the control signal has a first and second states, the remote station is characterized in that it comprises: means for receiving a synchronization signal from the base station, means for delineating, in relation to a synchronization signal, a time slot assigned to the remote station for receiving said control signal, means for detecting a sudden increase in energy during the allotted time interval, means for determining the state of the control signal depending on whether a sudden increase in energy was detected. 7. The remote station according to claim 11, characterized in that it also comprises means for receiving messages from the base station, depending on the detection of the sudden increase in energy. 8. The remote station according to claim 7, characterized in that it further comprises means for transmitting a second sudden increase in energy. 9. The remote station according to claim 8, characterized in that it further comprises means for transmitting a message depending on the transmission of the second sudden increase in energy. 10. A communication device for communicating with one or more communication stations, characterized in that it comprises: means for delineating a set of time intervals after a known time reference, each one of the time intervals within the set is associated with each of the communication stations, means for receiving a synchronization signal of a first communication device, means for determining, by means of the reception of the synchronization signal, the time reference, and means for transmitting a sudden increase in energy during the time interval associated with a target communication station. 11. A communication device for communicating messages with one or more communication stations, characterized in that it comprises: means for delineating a first set of »Time intervals after a time reference 15 known, each of the time intervals within the first set is associated with each of the communication stations, means for delineating a second set of time intervals after the time reference 20, each of the intervals within the second set is associated with each of the communication stations, means for transmitting a first sudden increase of energy during the time interval of the 25 first set associated with a communication station objectively depending on whether the first message is to be sent to the target communication station, means for transmitting the first message to the target communication station, means for detecting a second sudden increase in power • of a source communication station during the time interval of the second set which is associated with the originating communication station, means for receiving the second message of the originating communication station depending on whether the second sudden increase in energy was detected.