improves bit rate by allowing the transmission of several different signals on the same frequency and at the same time. 4.1.5. Physical signals 4.1.5.1. Downlink The primary synchronization signal (PSS) ensures the frequency synchronization of the OFDMA signal and timing synchronization at the half-frame level. The secondary synchronization signal (SSS) provides time synchronization at the frame level. The cell-specific reference signal (RS) is a signal specific to the cell used to perform coherent demodulation of the received signal which is based on the calculation of the transfer function of the radio channel. The MBMS single frequency network reference signal (MBSFN RS) is transmitted only in the physical multicast channel (PMCH) to perform coherent demodulation of the received signal. The UE-specific RS physical signal is a specific signal to the mobile used to perform coherent demodulation of the received signal, to measure the power of the received signal and for beamforming. The positioning reference signal (PRS) is used by the mobile to determine its location from the observed time difference of arrival (OTDOA) mechanism. The channel state information reference signal (CSI RS) improves the measurement of the received signal and the interference level from that supplied from the cell-specific RS physical signal. VoLTE and ViLTE The power of the CSI RS physical signal is either transmitted to determine the level of the received signal, or suppressed to measure the level of interference. 4.1.5.2. Uplink The demodulation reference signal (DM-RS) associated with the physical uplink shared channel (PUSCH) is used for estimation and synchronization of the PUSCH physical channel. The DM-RS physical signal associated with the physical uplink control channel (PUCCH) is used for estimation and synchronization of the PUCCH physical channel. The sound reference signal (SRS) allows the eNB entity to measure the quality of the signal for the uplink, in a frequency band higher than that allocated to the mobile. This mea