Power control – already being applied in 2nd and 3rd generation networks – has high potential for improvement of the performance of mobile networks. Main benefits are: 1. It can bring down the interference in up- and downlink and hence enhances the capacity of the networks. 2. Additionally it helps to keep down the uplink-power … Read more
RE – groups & CFI – Control Format Indication in LTE is as below. RE – groups In order to support DL control information mapping, RE-groups are defined. Four useful symbols are bundled, useful in the sense that RE’s carrying the cellspecific reference symbols are not available. The one cell-specific RS case is mapped in … Read more
The action of camping on provides access to services. The network provides different levels of service to a UE in either Idle mode or Connected mode. Three levels of services are defined: LIMITED SERVICE: emergency calls on an acceptable cell. Acceptable cell: UE may camp to obtain limited service like emergency call. The minimum set … Read more
Random access procedure is performed for the following five events: • Initial access from RRC_IDLE; • RRC Connection Re-establishment procedure; • Handover; • DL data arrival during RRC_CONNECTED requiring random access procedure; • UL data arrival during RRC_CONNECTED requiring random access procedure; E.g. when UL synchronization status is “non-synchronized” or there are no PUCCH resources for … Read more
S-CRITERION The cell selection criterion S is a pre-condition for suitable cells. The conditions for E-UTRAN, UTRAN FDD and GSM cells are listed in the figure. R – CRITERION – CELL RESELECTION The cell reselection evaluation process depends on whether Hierarchical Cell Structure (HCS) is used or not. In order to perform cell reselection UE … Read more
PLMN Selection Process in LTE The UE scans all RF channels in the UTRAN band according to its capabilities to find available PLMNs. On each carrier, the UE searches for the strongest cell according to the cell search procedure (refer cell searching) and read its system information in order to find out which PLMN the … Read more
Threre are four Different Methods to Combine OFDMA for handle Multiuser System. Plain OFDM: Normal LTE OFDM has no built-in multiple-access mechanism. This is suitable for broadcast systems like DVB-T/H which transmit only broadcast and multicast signals and do not really need an uplink feedback channel (although such systems exist too). Packet Statistical Multiplexing: It … Read more
The UE is requested to send either periodic or a periodic reports concerning • Rank indication (RI) Reports are applicable for closed- and open-loop spatial multiplexing. In case of open-loop TRI=1 corresponds to transmit diversity and TRI>1 to large delay CDD. • Precoding matrix indicator (PMI) PMI reporting is relevant for spatial multiplexing (open- and … Read more
Based on DCI formats In LTE Three types of allocation are used: type 0: DCI formats 1, 2, 2A type 1: DCI formats 1, 2, 2A type 2: DCI formats1A, 1B, 1C, 1D One bit in the header is indicating if DCI formats 1, 2, 2A are of type 0 or type 1. Type 0: … Read more
The scheduling is performed on cell basis. The two main functions are to decide which UE(s) shall be scheduled, the number of resources and the MCS to be applied. Furthermore the scheduler needs to be QoS aware. There is priority given to random access responses, control data, HARQ retransmissions. The channel quality may be taken … Read more