FDM in LTE Conventional multi-carrier operation as it is used for FDM works simply by selecting a number of center frequencies – one for each carrier to be used. The center frequencies must be spaced. In fact there is a trade-off between minimizing interference between different carriers and using the total bandwidth efficiently. In other … Read more
The price for the optimum subcarrier spacing is the sensitivity of OFDM to frequency errors. If the receiver’s frequency is some fractions of the subcarrier spacing (subcarrier bandwidth) then we encounter not only interference between adjacent carriers, but in principle between all carriers. This is known as Inter-Carrier Interference (ICI) and sometimes also referred to … Read more
RF engineering is a trade off between: required radio spectrum (bandwidth), speed of data transmission (bit rates) and complexity of implementation. The pulse form used to modulate complex data symbols to the radio carrier frequency is the major element of this story. Over the years several pulse forms and their associated pulse shaping filters have … Read more
The state-of-the-art design of the LTE air interface is characterised by OFDMA (DL) and SC-FDMA (UL) together with MIMO. The downlink modulation is based on OFDMA (Orthogonal Frequency Division Multiple Access). OFDMA is a variant of OFDM which has the advantage that receiver complexity is at a reasonable level, it can handle scalable bandwidth requirements … Read more
There Are Three Codes in CDMA PN Long Code,PN Short Code & Walsh Code. PN Long Code The Long Code is a PN sequence that is 242 – 1 bits (chips) long. The long code is used to encrypt user information. Both the base station and the mobile unit have knowledge of this sequence at … Read more
Mobile WiMAX frame structure Unlike Fixed WiMAX, which uses OFDM frames, Mobile WiMAX uses OFDMA frames. OFDMA allows multiple users to receive data from the base station at the same time. In this type of system, the downlink bursts from the base station are divided by a time offset and a frequency offset (sub-channel offset). … Read more
WiMAX antennas, just like the antennas for car radio, cell phone, FM radio, or TV, are designed to optimize performance for a given application. The figure above illustrates the three main types of antennas used in WiMAX deployments. From top to bottom are an omni directional, sector and panel antenna each has a specific function. … Read more
In an actual application, the system implements the modulation in this way: as shown above, I and Q channel sequences in the figure represent two channels of cyclic PN short code sequences. The cyclic period of each channel of PN short codes is 215. For different sectors, there are different starting locations of I … Read more
Handovers are a crucial aspect of LTE networks, as they ensure seamless connectivity as mobile devices move within the network. Types of Handover in LTE What are the different types of handover in LTE? Intra-frequency Handover: Description: Intra-frequency handovers occur when a mobile device moves within the same frequency band and connects to a different … Read more
Which Cell Parameters needs to Obtain in LTE? To provide the most critical information to the UEs, the eNodeB uses the BCH channel The information is sent on pre-defined time-frequency resources. This information is organized into different information blocks: The MIB, the Master Information Block. System Frame Number DL -downlink System Bandwidth Number of Transmit Antennas … Read more