4G LTE

Constellation in LTE In LTE (Long-Term Evolution), the term “constellation” typically refers to the modulation scheme used for transmitting data over the air interface. LTE uses Quadrature Amplitude Modulation (QAM) to encode multiple bits into a single symbol. The constellation diagram visually represents how the amplitude and phase of the modulated signals correspond to specific … Read more

The 3G LTE uses 3 Quadrature Amplitude Modulations (QAMs) depending on the radio quality. QAM uses both the amplitude and the phase. LTE devices use QPSK, 16QAM and 64QAM to modulate data and control information. The eNodeB supports all of these modulation techniques for the downlink direction. However, 64QAM is optional in the uplink direction. … Read more

LTE Architecture The LTE (Long-Term Evolution) architecture consists of several key components: User Equipment (UE): Mobile devices like smartphones or tablets used by end-users. Evolved NodeB (eNB): Base station responsible for radio communication with the UE. It includes the radio transceiver and performs functions like encryption and modulation. Mobility Management Entity (MME): Manages UE mobility, … Read more

In any two-way radio system, the radio pathlosses and the equipment output powers and sensitivities must be taken into account for both directions. This is especially true in a mobile network (e.g. downlink: BS to UE and uplink: UE to BS), where there are different characteristics for the uplink and downlink paths. These include, for … Read more

The system designer will need to determine the specific RF link budget parameters to be used when designing the system. The following figure shows the typical gains and losses that are encountered in the RF path. An RF link budget must be determined for each sector of each site. The RF link budget for each … Read more

Transmit Diversity Gain in LTE In Long-Term Evolution (LTE) wireless communication systems, transmit diversity gain plays a crucial role in enhancing the reliability and performance of data transmission. Transmit diversity involves the use of multiple antennas at the transmitter to improve the quality of the received signal at the receiver. One common technique employed in … Read more

Modulation Techniques in LTE LTE devices use several modulation techniques to modulate data and control information. These modulation techniques include: QPSK (2 bits per symbol), 16QAM (4 bits per symbol), and 64QAM (6 bits per symbol). All of these modulation techniques are supported in the downlink direction; and all but 64QAM, which is optional, are … Read more

MULTIPLE ANTENNA TECHNOLOGY IN LTE The use of multiple antenna technology allows the exploitation of the spatial domain as another new dimension. This becomes essential in the quest for higher spectral efficiencies With the use of multiple antennas the theoretically-achievable spectral efficiency scales linearly with the minimum of the number of transmit and receive antennas … Read more

MULTICARRIER TECHNOLOGIES IN LTE Adopting a multicarrier approach for multiple access in LTE was the first major design choice. The choice of multiple-access schemes was made in December 2005, with OFDMA being selected for the downlink, and SC-FDMA for the uplink. Both of these schemes open up the frequency domain as a new dimension of … Read more

BEAMFORMING in LTE If some knowledge of the downlink channels of the different transmit antennas, (more specifically some knowledge of the relative channel phases) is available at the transmitter side, multiple transmit antennas can be used to shape the overall antenna beam in the direction of a target receiver. In general, such beamforming can increase … Read more