Method for processing in a telecommunication system and associated telecommunication module

0001The present invention relates to a processing method in a telecommunication system comprising a first wireless communication module according to a first wireless communication protocol, said first module being adapted to receive a signal comprising at least a first signal according to the first protocol a wireless transmission channel and comprising an automatic calculation block gain which determines a current gain value based on the received signal in said wireless transmission channel and a suitable amplifier for amplifying said received first signal based on said current value gain determined by said received signal.

0002Is known from document <patcit id="pcit0001" dnum="US20070064835A1"><text>US 2007/0064835 A1</text></patcit> a method of carrying out, following the receipt of a notification, an against-measurement in order to reduce interference effects.

0003Also known document <patcit id="pcit0002" dnum="US20040239559A1"><text>US 2004/0239559 A1</text></patcit> a method of reducing interference by detecting a jamming signal and generating a signal synchronized with said jamming signal.

0004It is known, moreover, the document <patcit id="pcit0003" dnum="WO0106669A1"><text>WO 01/06669 A1</text></patcit> a method implemented at a receiver and a transceiver and of anticipating the intervals during which the transceiver is operative to desensitize the receiver during said gaps.

0005For example, ATC transponder (in English "Air Traffic Control") on board aircraft are used to communicate the position, altitude and / or identity of the aircraft. This communication can be a response generated by ATC following the reception of an interrogation sent by a secondary radar. This secondary radar is associated with a primary radar which effects only detecting the position of the aircraft in range and azimuth by means of receiving an echo.

0006This response may also be generated because queries from other aircraft within the surrounding airspace. These questions are issued by a system called TCAS ( "Traffic Collision Avoidance System") to prevent collisions.

0007In the case of ATC responses corresponding to 1090 MHz frequency pulse trains (megahertz) conveying the position messages, altitude and / or identity of the aircraft, the second harmonic of an ATC answer is centered on a frequency Fr_h2, Equal to 2180 MHz and a power level of the order of several watts.

0008The applicant wishes to acquire the planes of mobile telecommunications, for example of LTE, which receive flows from emitter to the ground using a radio frequency band that contains the second harmonic.

0009Or the reception capacity of these embedded LTE telecommunication means in a plane is heavily impacted when ATC responses emission by the also boarded the aircraft transponder, because the pulse trains and invalidates blind, due to the mechanism adaptive gain of the telecommunications, reception, and this for a very long time including the de-sensitization of time and re-sensitization of the receiver is necessary for the latter to find the gain allowing it to handle again correctly LTE signals received.

0010Indeed, after each pulse train, the gain decreases sharply and for the duration of re-sensitization, the gain is insufficient to properly handle the LTE signal.

0011This results in a loss of throughput and an increase in the LTE communication latency can render inoperative the means of telecommunication LTE when emissions from the transponder are common, especially when the pulse train recurrences are greater than or equal to 500 trains per second, as typically encountered.

0012For this purpose, in a first aspect, the invention provides a method of processing in a telecommunication system of the aforementioned type characterized in that the telecommunication system comprising a second wireless communication module adapted to intermittently output second signals over the wireless communication channel according to a second communication protocol, each second signal being of duration less than T_maxThe method comprises a step in which when a second signal is determined by the block automatic gain calculation, as present in the signal received by the first module in said wireless transmission channel, a current value of gain is then determined by the calculation block of automatic gain independently of the power of said second signal.

0013The proposed solution reduces the disadvantages of the prior art, especially to limit the impact of the issuance of the second signal on receipt of the first signal on said channel.

0014In embodiments, the treatment method in a telecommunication system according to the invention further comprises one or more of the following:<ul><li>the automatic gain calculation unit detects an increase in power of said received signal and for, upon detection of said increase, only updates the value of the gain depending on the power signal and increased only if the increase in the amplitude persists beyond a period equal to T_max ;</li><li>the automatic gain calculation block freezes the present value of the gain from said detection for a time at least equal to T_max or equal to the minimum between T_max and how long persists the power increase;</li><li>in a nominal operating mode of the automatic gain calculation block, said automatic gain calculation block determines the current gain value based on the received signal power in said wireless transmission channel;</li></ul>said method comprises the following steps when a second signal is to be transmitted by the second wireless communication module:<ul><li>estimating a function of the delay time required for transmission by the second wireless communication module of said second signal;</li><li>subsequent to said estimate, triggering an auxiliary mode of operation of the automatic gain calculation block, for a duration equal to said estimated time delay during which the second signal is emitted, wherein the automatic gain calculation block determines a value current gain independently of the power of the second received signal into said wireless transmission channel;</li><li>a second signal to be transmitted is a response to a message indicating a code and received by the second module, and said time required for transmission of said second signal is estimated based on said code;</li><li>the telecommunication system is installed on board a mobile building, the first wireless communication module is a receiver mobile radio adapted to communicate with a remote mobile radio network and the second wireless communication module is a transponder adapted to communicate with a remote and / or a remote transponder radar;</li><li>the first wireless communication protocol is a protocol LTE;</li><li>the second signal from the signal received in said wireless transmission channel by the first wireless communication module is amplified by the amplifier based on said updated value of calculated gain; </li><li>the first wireless communication protocol is designed so that the first module detects that it did not correctly receive a signal for him and for following said detection, to correctly reconstruct or re-transmit said first signal to the second module;</li><li>the first wireless communication protocol is designed so that the first module detects that it did not correctly receive a signal for him and for following said detection, to correctly reconstruct or re-transmit said first signal to the second module.</li></ul>

0015In a second aspect, the present invention provides a wireless telecommunication module according to a first wireless communication protocol, adapted to receive, over a wireless transmission channel, a signal comprising at least a first signal according to the first protocol and comprising an automatic gain calculation block adapted to determine a gain value as a function of the received signal in said wireless transmission channel and a suitable amplifier for amplifying said received signal based on a gain value determined by the automatic calculation block gain; said wireless communication module being intended for a telecommunication system comprising a further wireless communication module adapted to intermittently output second signals over the wireless communication channel according to a second communication protocol, each second signal being of duration below T_max, said wireless communication module according to a first wireless communication protocol being characterized in that the block automatic gain calculation is adapted to, when it determines that a second signal is present in the received signal, determining a current value gain independently of the power of said second signal.

0016In embodiments, the wireless communication module further comprises one or more of the following:<ul><li>the automatic gain calculation block is adapted to detect an increase in power of said received signal and for, upon detection of said increase, not updating the value of the gain as a function of the power signal and increased only if the increase the amplitude persists beyond a period equal to T_max ;</li><li>block automatic gain calculation is suitable to freeze the present value of the gain from said detection and for a delay equal to T_max or equal to the minimum between T_max and how long persists the power increase; </li><li>in a nominal operating mode of the automatic gain calculation block, said automatic gain calculation block is adapted to determine the current value of gain depending on the received signal power in said wireless transmission channel; and when a second signal is to be transmitted by the second wireless communication module, estimating a function of the delay time required for transmission by the second wireless communication module of said second signal and trigger a mode of operation of the auxiliary block automatic gain calculation, for a period at least equal to said estimated time delay during which the second signal is emitted, wherein the automatic gain calculation block is adapted to determine a current value of gain independently of the power the second received signal into said wireless transmission channel;</li><li>a second signal to be transmitted is a response to a message indicating a code and received by the second module, and said time required for transmission of said second signal is estimated based on said code;</li><li>the wireless communication module is intended for a telecommunication system on board a mobile building, said wireless communication module being a receiver mobile radio adapted to communicate with a remote mobile radio network and said second signals being transmitted by a transponder adapted to communicate with a remote radar and / or a remote transponder, and</li><li>the first wireless communication protocol is a protocol LTE.</li></ul>

0017These features and advantages of the invention will become apparent from reading the following description given solely by way of example and with reference to the accompanying drawings, wherein:<ul><li>the <figref idrefs="f0001">figure 1</figref> shows a view of a wireless telecommunication system in one embodiment of the invention;</li><li>the <figref idrefs="f0001">2</figref> represents steps of flowchart of a method in an embodiment of the invention;</li><li>the <figref idrefs="f0002">3</figref> is a partial view of the transceiver 4 in one embodiment.</li></ul>

0018The <figref idrefs="f0001">figure 1</figref> is a view of a system 2 for wireless telecommunication in one embodiment of the invention.

0019In this case, the system 2 wireless telecommunications is put on a plane 1.

0020The system 2 wireless telecommunication comprises a transponder 3 and a transceiver LTE4.

0021The transponder 3, ATC type is adapted to receive query messages from a remote device 12 (eg, a secondary ground radar or transponder aboard another plane etc.).

0022These interrogatory messages require the supply by the transponder 3, the plane 1 characteristics such as the identity of the aircraft and / or its current altitude and / or position and / or a code indicating its operational position (radio failure, diversion, etc.) and comprise at least a respective polling code indicating which of these characteristics is required (or which of these characteristics are required) in accordance with one of three modes ATC a, C or S.

0023Such a query message in the present case takes the form of a pulse train with a frequency Fi = Fi for example 1030 MHz.

0024The transponder 3 is designed to prepare and issue a response message to the ATC interrogation message.

0025The content of an ATC response message includes the characteristic required of the aircraft 1 (s) in the interrogation message.

0026In the considered case, an ATC response message takes the form of a pulse train transmitted at a radio frequency Fr, e.g. Fr = 1090 MHz, and the length of the train is at most T_max = 120 microseconds (microseconds) or according to the transmitted characteristics, the train length is either 25 microseconds or 120 microseconds.

0027The second harmonic of an ATC response message is centered on a frequency Fr_h2Equal to 2180 MHz and lasts about 10 MHz.

0028The power of the second harmonic level is typically a few watts.

0029The transceiver LTE 4 is suitable for transmitting, receiving, respectively, to the data, respectively from, at least one base station 11, eNode B type, soil and arranged within radio range of the transmitter LTE transceiver 4.

0030These emissions data and approvals are achieved in accordance with the LTE protocol (in English "Long Term Evolution") defined by 3GPP consortium.

0031The reception band of the transceiver 4 is the band B_recWhich is the band [2170 MHz, 2185 MHz] in the case considered.

0032The transceiver includes an antenna LTE 4 6 LTE signal reception in said strip. The transceiver LTE 4 comprises a circuit for receiving signals received via the antenna 6 and corresponding to band B_rec, Said receiving circuit comprising an amplifier stage 7 and block 8 of automatic gain control.

0033The antenna 6 receives a current signal in the band B_rec and provides, after filtering of the signals in this band, this signal current received at the amplifier 7.

0034The transceiver LTE 4 further comprises a transmission circuit LTE signals (not shown).

0035The amplifier stage 7, for example of the low noise amplifier, LNA said (standing for "Low Noise Amplifier"), is adapted to amplify the current signal that is provided as input by the antenna 6, multiplying a gain whose value is supplied to it by the block 8 automatic gain control.

0036This amplified signal provided by the amplifier stage 7 then undergoes treatments implemented by the receiving circuit of the transceiver 4, including the baseband conversion, processing baseband and demodulating LTE .

0037The amplified signal is also provided at the input of block 8 automatic gain control.

0038Block 8 automatic gain control is adapted to determine, based on recently received signal in band B_rec (Typically the most recently received signal is the entire received signal and supplied by the antenna 6 from a time window of duration T₀ ending at the current instant t considered, T₀ fixed according to the embodiment), the current value of gain applied by the amplifier 7 on the current signal received.

0039The purpose of this adaptive gain is to obtain in output of the stage amplifier 7 a substantially constant amplitude signal, equal to a target amplitude value (typically the gain is low when the power of the LTE signal is received lately large, and the gain is strong when the power of LTE recently received signal is low, the gain is a decreasing power of the power of LTE signal received recently).

0040According to the invention, block 8 of automatic gain control is adapted to determine a current value of gain, depending on the recent received signal and supplied by the antenna 6, independently of the power of a response message ATC transmitted by the transponder 3 when it is determined by the block 8, that such ATC response message is part of the current signal received ..

0041Thus according to the invention, the transceiver 4 is adapted to implement the set of steps 100 comprising steps 101, 102, 103.

0042In step 101, the current signal, called S (t) received by the antenna 6 in band B_rec is supplied at time t 7 to the amplifier stage.

0043In a step 102, the stage amplifier 7 amplifies the current received signal S (t) by the current value provided by the block 8 of the automatic gain control and supplies the signal thus amplified, named S_at(T), in parallel to the portion of the receiving circuit in charge of the LTE demodulation and block 8 of automatic gain control.

0044In step 103, block 8 automatic gain control determines a current gain value based on the received signal (ie according to S_at(T)).

0045And where ATC response message transmitted by the transponder 3 is part of the received signal, block 8 automatic gain control determines a current gain value independently of the power of the ATC response message.

00468 automatic control block gain delivers to the amplifier stage 7 the discounted present value of fixed gain.

0047In a particular implementation of a first embodiment, reference is made to the portion of the transceiver shown in 4 <figref idrefs="f0002">3</figref>.

0048The transceiver 4 comprises the antenna 6, the amplifier stage 7, an analog-digital converter 20, a digital downconverter 21, also called DDC 21, (in "Digital Down Concerter") and block 8 automatic gain control.

00498 automatic gain control block comprises an envelope detector 9, a calculation block 10, a digital-analog converter 22 and a controller gain calculation 25.

0050The gain calculation controller 25 includes, in the particular case, a low-pass filter 11, a subtractor 12, a hysteresis comparator 13 and a delay device 14.

0051This treatment eliminates the signal addressed to the adaptation of the gain equal duration components or less than T_max.

0052Thus, in this first embodiment of the invention, the following sub-steps take place during step 102.

0053The signal received by the antenna, which is then applied a filter bandwidth band pass band B_rec is supplied to the amplifier stage 7. The amplifier stage 7 applies the signal that it receives as input the current gain then calculated by the block 8 of the automatic gain control. The thus amplified signal is digitized by the analog-digital converter 20, down-converted by the DDC 21, and then is sent, on the one hand to LTE demodulation device, on the other hand to the block 8 of the automatic gain control .

0054In block 8 of automatic gain control, the envelope of the input signal given is detected by the envelope detector 9. And the signal from the envelope detector 9 is sent, on the one hand to the calculation block 10, on the other hand to the gain calculation controller 25 (point A).

0055The subtractor 12 takes the difference between the amplitude of the incoming signal at point A and the magnitude of the average value of said signal (received at point B), the average value obtained by passing said signal in the low-pass filter 11 frequency cut much less than the inverse of the desired reaction time for the gain calculation controller 25 (typically in the case considered, the cutoff frequency is chosen equal to 800 Hz).

0056The difference (obtained in step C) between the incoming signal and its average value is then applied to the positive input of the magnitude comparator 13 with hysteresis. On the negative input of comparator 13 is applied a high threshold value. The effect of the hysteresis comparator 13 results in that the crossing of the upper threshold by the signal applied to the positive input will result in a tilting to the high state of the comparator output if threshold crossing corresponds to an increase of the signal amplitude. The changeover to the low state of the comparator output will intervene if the signal applied to the positive input to a null value and if this threshold crossing corresponds to a decrease of the signal amplitude.

0057And a sharp increase in the input signal from the controller 25 (point A) therefore induce a tilt to the high state of the output of the comparator 13 (D). A return to the initial amplitude of the signal will provide the comparator output 13 to low.

0058The output of comparator 13 (point D) is applied, on the one hand to the timing device of the trigger input 14 and secondly to the reset input of the delay device 14. The portion of the low to high (rising edge) on the trigger input of the delay device 14 triggers the activation of a control signal (point E) for a slightly longer than the duration of the longest burst time delay ATC signal (which are here 120 ms). The transition from the high state to the low state (falling edge) of the reset input of the delay device 14 interrupts the activation of a control signal that was triggered previously (E).

0059A sharp increase in the device the input signal (point A) therefore induce an activation trigger control signal (point E) for a period of 120 microseconds. The end of the timer interrupts the activation of the control signal. A return to the initial amplitude of the signal interrupts the activation of the control signal (in the case, for example, a return to the initial amplitude after a sharp increase in the signal for a duration of 25 ms).

0060The control signal above (point E) is applied to a blocking input of the gain calculation block 10.

0061Activation of the control signal requires the gain calculation block 10 to maintain a constant gain provided to the amplifier stage 7 (point F), and a value equal to the value of what this gain at the outbreak of the activation of the control signal. The interruption of the control signal allows the gain calculation block 10 to update the gain according to the value of the signal present on its input (the so determined gain being a decreasing function of the power of this signal so as to obtain in output of amplifier 7 a constant amplitude).

0062A sharp increase in the signal at point A will thus result in a corresponding variation in the gain applied by the amplifier stage 7 (point F) only if the new value of the input signal lasts more than 120 microseconds. An increase "moderate" or a decrease in the signal at point A will result in a variation of the gain applied by the amplifier stage 7 as if the gain calculation controller 25 was absent (this is transparent to changes "natural" LTE signal ).

0063The block of the reaction time of 8 automatic gain control on the appearance of a high-power signal in the band B_rec is short (de-sensitization), but the re-sensitization time is longer (several ms) in order not to blur the modulation envelope of the signal received.

0064This treatment has the function to eliminate rapid variations in the received signal level (duration less than T_maxHere T_max = 120 microseconds) in order not to be considered in the calculation of adaptive gain block 10 to calculate the level changes corresponding to a change of the useful signal for LTE receiver, the type slow fading, antenna masking .. .

0065A sudden onset of a high level signal on the antenna 6, the following cases may arise:<ul><li>the level of variation is related to a sudden change of the useful signal: the reaction block 8 of automatic gain control, and therefore the adaptation of the gain, is delayed t_maxHere T_max = 120 microseconds: the receiver is "blinded" during a maximum period of T_max ie the signal provided by the amplifieur will be too strong compared to the target amplitude for 120 s; </li><li>the level variation is due to the emission of an ATC pulse train 25 microseconds by the transponder 3: the reaction of the box 8 of the automatic gain control after this change is inhibited by the action of the filter 9; the receiver is "blinded" during a maximum period of T_max 120 microseconds, but there is no dead time of re-sensitization of several ms at the end of the show the pulse train as experienced in the operation of the prior art;</li><li>the level variation is due to the emission of a pulse train ATC T_max = 120 microseconds by the transponder 3: the block of reaction 8 automatic gain control after this change is inhibited by the action of the filter 9; the receiver is "blinded" for a time T_max 120 microseconds, but again there is no down time to re-sensitization of several ms to the end of transmission of the pulse train like experienced in the operation of the prior art.</li></ul>

0066In a second embodiment of the invention, the automatic gain control block 8 is adapted to operate according to two alternative modes of operation: the nominal mode and the auxiliary operation mode.

0067In one embodiment, the switch to the auxiliary operation mode is triggered by the receipt by the block 8 automatic gain control of a notification by the transponder 3 to the block 8 via a communication bus indicating the imminent sending an ATC response message by the transponder 3.

0068In one embodiment, the duration T_train the response message will be sent (this time depends on the corresponding query message) is indicated in the notification.

0069In the nominal operating mode, said automatic gain control block 8 determines, in step 102, the current value of gain G depending on the power of the recently received signal in said wireless transmission channel, ie based on S (t-θ) for all θ between 0 and T₀.

0070In the alternate mode of operation of block 8 of automatic gain control, automatic gain control block determines a current gain value G (t) based on a gain calculated by the block 8 of the automatic gain control before switch to auxiliary mode operation (or a predetermined value, for example corresponding to an average gain of an LTE signal received without presence of response ATC).

0071And block 8 of AGC is adapted to switch to auxiliary mode operation just before a pulse train is issued by ATC transponder 3, to stay in this mode of operation for auxiliary timer and a TEMP to switch from the alternate mode of operation to nominal operation mode after the timer TEMP.

0072SPECT delay value is chosen at least equal to the issue of duration of the pulse train.

0073According to embodiments, TEMP is set equal to the transmission duration of said pulse train T_train (Equal to 25 or 120 microseconds depending on the type of response) or equal to the maximum duration T_max. Or TEMP is set equal to the sum of T_train (Or T_max) And t₀.

0074The invention reduces the disadvantages of the prior art, especially to limit the impact of the pulses of the transponders response messages on LTE communications at a level substantially corresponding to the actual duration of transmission response messages.

0075In addition, in various embodiments, it will be detected by the transceiver LTE 4 and / or the eNode B 11, if data transmitted from the eNode B 11 were not received by the LTE transceiver 4, thanks to algorithms reliability of LTE protocol transmissions. Transmission errors due to missing data are corrected by the transceiver 4 with redundancies in the data received (and without the need for retransmissions) or when the missing data is retransmitted.

0076Such algorithms are, for example algorithms H-ARQ (English "Hybrid Automatic Repeat reQuest") and RLC (English "Radio Link Control") in particular. H-ARQ is particularly within 1 to 2 milliseconds, which can greatly limit the consequences of blindness and make it imperceptible to the type of data or voice communications LTE.

0077In the particular embodiment described above, a harmonic of the main signal from the transponder and the reception band of the LTE transceiver included a channel; the invention can of course be used in a case where the main signal itself transmitted by the transponder and the reception band LTE the module share the same channel.

0078The invention has been described above in relation to a transponder and a transceiver LTE. Of course, in another embodiment of the invention, the transponder and the LTE transceiver are, one and / or the other, be replaced by any other RF equipment using a common radio frequency channel.

0079In the particular embodiment described above, the recording time can take two alternative values; in other embodiments, the length of messages can take any number of values.

0080Moreover, in the embodiment described above, the automatic gain control is performed on the signal after amplification. In another embodiment there is provided on the signal before amplification.