摘要:
According to the method, a physical transmission channel is split into a plurality of logic channels which may be dedicated to different communications. Each logic channel consists of time slots having a same duration and the same rank in successive frames of constant length. At least one of the logic channels is split into a plurality of sub-channels dedicated to different communications. Groups of k successive time slots (k being an integer greater than 1) are allocated to each logic sub-channel. The groups are time distributed in a regular way and k is so selected that N be different from (m.k+1) where m is an integer and N is the number of time intervals necessary for reconstructing an information block.
摘要:
A signal of OFDM type received in a radio receiver via a propagation channel includes symbols distributed according to frequency and time. The receiver determines likelihoods of the symbols, decodes the received signal to yield a decoded signal as a function of the likelihoods of the symbols, and estimates an instantaneous noise power of the received signal as a function of a difference between the received signal and a reconstructed noise-free signal derived from the decoded signal. A filtering module determines a bounded distribution of the instantaneous noise power as a function of frequency and/or time, and filters the distribution to yield a filtered noise variance as a function of a frequency and/or time parameter of the propagation channel. A corrector weights the likelihoods of the symbols of the received signal to be decoded as a function of the filtered noise variance.
摘要:
A method for estimating a transmission channel from a multicarrier signal transmitted through said transmission channel, comprising real pilot symbols and so-called pure imaginary pilot symbols, consists in selecting one or several values zk of the received signal corresponding respectively to one or several real pilot symbols, and one or several values zl of the received signal corresponding respectively to one or several pure imaginary pilot symbols. The pilot symbols are sufficiently close both in frequency and in time such that it can be assumed that the fading of the signal through the transmission channel has a complex value α substantially identical for the symbols. An estimated value {circumflex over (α)} of α for the pilot symbols concerned is then determined by minimizing a least square equation involving the values zk and the values zl.
摘要翻译:一种用于从包括实际导频符号和所谓的纯虚拟导频符号的所述传输信道发射的多载波信号估计传输信道的方法在于选择接收信号的一个或多个值z k 分别对应于一个或几个实际导频符号,以及分别对应于一个或几个纯虚拟导频符号的接收信号的一个或几个值z 1。 导频符号在频率和时间上均足够接近,使得可以假设通过传输信道的信号的衰落具有对于符号实质上相同的复数值α。 然后,通过使涉及值z z和z z的值的最小二乘方最小化来确定相关导频符号的α的估计值(对于(α)}) 。
摘要:
A method of synchronization on the uplink channel of a Simulcast network with a plurality of fixed receivers (BS1-BS4) and a selection unit (20), comprises the following steps. All the receivers are placed in a synchronization search mode (702), in which they search for a synchronization pattern sent by the mobile terminal over the uplink channel. When a receiver detects the synchronization pattern, it produces an initial synchronization context (SC3(0)), which indicates the delay of the radio signal relative to a time reference of the network, and transmits it (705) to the selection unit. The latter broadcasts it (707) to all the receivers that use it to start processing the radio signal. Then, each receiver maintains its synchronization context and transmits it (708-712) to the selection unit on each frame. At regular intervals, the value of an updated synchronization context (SC2(i)) is broadcast (714) to the receivers. Advantage: the synchronization of a receiver which begins to receive the radio signal during a call or alternate turn is facilitated.
摘要:
A transmitter outputs a radio signal formed from a first baseband signal incorporating a synchronization signal. The recipient obtains a second baseband signal from the received radio signal, detects the synchronization signal in a portion of the second baseband signal in order to compute synchronization parameters and/or parameters for estimating a radio transmission channel, and uses the computed parameters to demodulate another portion of the second baseband signal and extract the transmitted information from it. The synchronization signal contains a synchronization pattern selected by the transmitter on the basis of signalling information to be supplied to the second station. The receiver searches several patterns in the second baseband signal in order to obtain the signalling information depending on the detected pattern.
摘要:
A synchronization method includes selecting, at a mobile station, at least one periodic pseudorandom sequence (PN) which corresponds to, and is synchronized with, the reference sequence transmitted by a base station on a pilot channel, and received by the mobile station over a propagation path, this operation being carried out regardless of the frequency deviation between the transmitter and the receiver. Various possible sequences are tested by calculating the quantities E[s(t).multidot.s*(t-.tau.)] and E[s(t).multidot.s*(t)], where E[.multidot.] designates the mean value calculated over a predetermined integration time, .tau. designates a predetermined delay, and s(t)=r(t).multidot.c(t) designates the product of the received base band signal r(t) and the value (c(t)) of the tested sequence, and by calculating the ratio .vertline.E[s(t).multidot.s*(t-.tau.)][.vertline./Es(t).multidot.s*(t)]. The sequence under test is selected if the ratio exceeds a predetermined threshold.
摘要:
To reduce interferences in signals received by a receiver through a propagation channel, each including symbols distributed according to frequency and time dimensions and corresponding to a common emitted signal, the receiver weights an estimate of the emitted signal and the received signals by weighting vectors evolving in vector subspaces representing time variations and frequency variations of the channels for propagating the signals between an emitter and the receiver. These vector subspaces are defined by matrices, some columns of which are suppressed as a function of frequency and time constraints of the channel. The receiver minimizes a function of the difference between the sum of weighted received signals and the weighted estimate of the emitted signal in order to estimate the emitted signal as a function of the weighting vectors and the received signals.
摘要:
A method of synchronization on the uplink channel of a Simulcast network with a plurality of fixed receivers (BS1-BS4) and a selection unit (20), comprises the following steps. All the receivers are placed in a synchronization search mode (702), in which they search for a synchronization pattern sent by the mobile terminal over the uplink channel. When a receiver detects the synchronization pattern, it produces an initial synchronization context (SC3(0)), which indicates the delay of the radio signal relative to a time reference of the network, and transmits it (705) to the selection unit. The latter broadcasts it (707) to all the receivers that use it to start processing the radio signal. Then, each receiver maintains its synchronization context and transmits it (708-712) to the selection unit on each frame. At regular intervals, the value of an updated synchronization context (SC2(i)) is broadcast (714) to the receivers. Advantage: the synchronization of a receiver which begins to receive the radio signal during a call or alternate turn is facilitated.
摘要:
An elongate reaction vessel and process includes at least two stages in the vertical direction in which an endothermic or exothermic catalytic reaction is carried out and comprises: a catalytic reaction zone (12a, 12b) per stage (6, 7); introducing (2) a reaction fluid to a stage adapted for transverse motion of the fluid across the whole vertical extent of the reaction zone; introducing and extracting the catalyst; a heat exchanger (5a) for reaction fluids located inside the vessel between two successive reaction zones; means (6) for transporting reaction fluids from one stage to another preferably connected to the exchanger of the stage under consideration and to the inlet for reaction fluids of the subsequent stage; and means for recovering reaction fluids downstream of the last stage. The temperature variation in each zone and the temperature level are respectively adjusted by the thickness of each zone and by heat exchange.
摘要:
A method of management for operating a first system of communication of the broadband type communication system emitting over a first frequency range, and a second system of communication of the narrow band type communication system emitting over a second frequency range, the first system and the second system using all or part of a same frequency band, such common frequency band being called a crossover frequency band for both systems, the method including: embodying a scan operation from at least the crossover frequency band of the two systems using a scan device from the first communication system; identifying, after the scan operation, the frequency channels used by the second communication system; adapting the operating of the first communication system within the frequency channels identified as being used by the second communication system.