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 employed, at least in suitable … Read more
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 flexibility in the system, … Read more
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 the signal-strength at … Read more
LTE OFDMA and Downlink Frame Structure Details Downlink OFDMA time-frequency multiplexing LTE Spectrum Flexibility and Bandwidth FDD downlink frame structure detailed TDD frame structure LTE (any OFDM/OFDMA) band is made up of multiple small spaced channels and we call each of these small channels as “Sub Carrier”. Space between the chhanel and the next channel … Read more
A parallel 3GPP R8 project to LTE and SAE is the Evolved High Speed Packet Access, eHSPA, project (also referred to as HSPA+). The proposed eHSPA features represent a logical evolution from today’s HSDPA and HSUPA systems. Roughly speaking, the eHSPA project focuses on three areas: • Optimising HSPA for real-time packet data services, like … Read more
A (rather long) list of general requirements has been set up as guidelines for the standardization work related to the EPC. Some of those are: • 3GPP and non-3GPP access systems shall be supported. • Scalable system architecture and solutions without compromising the system capacity (e.g. by separating CP from UP). • CP response time … Read more
Figure shows the network architecture of the Evolved Packet Core (EPC). The EPC consists of three main nodes: the Mobility Management Entity (MME), the Serving Gateway (SGW) and the Packet Data Network Gateway (PGW). The MME may be co-located with the SGW, and the SGW may be co-located with the PGW. Hence, the standard allows … Read more
The uppermost evolution track shown in Figure is that developed in the 3rd Generation Partnership Project (3GPP), which is currently the dominant standards development group for mobile radio systems and is described in more detail below. Within the 3GPP evolution track, three multiple access technologies are evident: the ‘Second Generation’ GSM/GPRS/EDGE family1 was based on … Read more
When the radio wave propagates in the air, the electric field direction changes regularly. If the electric field direction of radio wave is vertical to the ground, the radio wave is vertical polarization wave If the electric field direction of radio wave is parallel with the ground, the radiowave is horizontal polarization wave Propagation of … Read more
Open loop power control together with optional power ramp-up is used during the random access process at the beginning of the connection until more accurate control information is available. Power loss due to transmission distance depends on to the increase of the distance between NodeB and the UE. In such a case, feedback information from another side is not … Read more