What is Basic behind MIMO for LTE MIMO and other transmit spatial diversity scheme is a newer application than receive diversity and has become widely implemented only in the early 2000s. As the signals sent from different transmit antennas interfere with one another, processing is required at both the transmitter and the receiver in order … 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
MIMO is effectively radio antenna technology because multiple antennas are used at the transmitter and receiver to allow a variety of signal paths to transmit the data, with separate paths selected for each antenna so that multiple signal paths can be used. The basic mechanism behind MIMO is linear algebra. If we e.g. transmit N … Read more
Fully packet-oriented mobile broadband network providing: – Peak data rates of 100 Mbps (DL) and 50 Mbps (UL) – Very low latency – Seamless and lossless handover – Sophisticated QoS to support important real time applications such as voice, video and interactive gaming – Support for terminal speeds of 150-500 Km/h and cell ranges of … Read more
SU-MIMO = Single User MIMO It is the most common form of MIMO. Each user is served by only one BS and it occupies the resource exclusively, including time, frequency. It can be applied in the uplink or downlink. But it is generally applied only in DL. The UE can easily have 2 antennas in … Read more
MIMO-MU = Multi user It is used only in Uplink. MIMO-MU does not increase the individual user’s data rate but it does offer cell capacity gains that are similar to, or better than, those provided by MIMO-SU. The UE does not require the expense and power drain of two transmitters, yet the cell still benefits … Read more
MIMO = Multiple Input Multiple Output 2 or more transmitters and 2 or more receivers. MIMO transmits several streams whereas SIMO or MISO transmits only one stream. If there are N streams, there will be at least N antennas (here only 2). By spatially separating N streams across at least N antennas, N receiverswill be … Read more
The third assumption—that the background noise is Gaussian and uncorrelated with the transmissions—is especially suspect in a cellular MIMO system. All well-designed cellular systems are by nature interference limited: If they were not, it would be possible to increase the spectral efficiency by lowering the frequency reuse or increasing the average loading per cell. In the … Read more
There are two ways to transmit training symbols: preamble or pilot tones. Preambles entail sending a certain number of training symbols prior to the user data symbols. In the case of OFDM, one or two preamble OFDM symbols are typical. Pilot tones involve inserting a few known pilot symbols among the subcarriers. Channel estimation in … Read more
SU-MIMO is one of the key technologies in LTE Rel 8. There are two major operations under SU-MIMO: transmit diversity and spatial multiplexing. Transmit diversity is an efficient way to improve the reliability of a system. Accordingly, it is used in LTE Rel-8 for control channel and data channel of cell edge mobile stations (called … Read more