TelecomStudy18

Positioning reference signals are used for OTDOA User Plane Location Support. Positioning reference signals are transmitted with a periodicity Tprs[ms], as specified by prsPeriod . At each transmission occasion the position reference signals are sent in n,subf,con consecutive DL subframes. The number of consecutive DL subframes can be specified by nConsecutiveSubframes . In the figure below an example of the transmission scheme for PRS subframes is shown.   To minimize the interference in the PRS subframes PDSCH is not scheduled in any RB in those subframes. Also note that PBCH, PSS and SSS all have higher priority than PRS. For a configuration with two antennas, PRS is transmitted from one antenna at the time. The same antenna is used the entire PRS occasion. For more information, refer to OTDOA User Plane Location Support. The more PRS subframes, the more accurate will the OTDOA positioning be.  This comes at the expense of less resource available for PDSCH. The fr...

To demodulate different downlink physical channels coherently, the UE requires complex valued channel estimates for each subcarrier. Known cell-specific reference symbols are inserted into the resource grid. The cell-specific reference signal is mapped to REs spread evenly in the resource grid, in an identical pattern in every RB. When transmitting with several antennas, each antenna must transmit a unique reference signal. When one antenna transmits its reference signal, the other antenna must be silent. The mapping of the cell-specific reference signal on the resource grid therefore depends on the antenna configuration, see Figure. The pattern of cell-specific reference signals can be shifted in frequency compared to figure below. Which one of the six possible frequency shifts to use depends on the Physical Cell Identity (PCI) sent on Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS). Holes are REs that must be silent because the cell-sp...

Time Domain Structure In the time domain, the signal is structured in the following parts: Time Domain Signal Structure Structure Element Description Radio Frames 10 ms length Subframes 1 ms length. One frame consists of 10 subframes. Slot 0.5 ms length. One subframe consists of two slots. OFDM symbol Approximately 71.4 μ s length. One slot consists of 7 OFDM symbols.     Frequency Domain Structure Orthogonal Frequency-Division Multiplexing (OFDM) utilize a large number of subcarriers. Each subcarrier is orthogonal to all other subcarriers. Subcarrier spacing is equal to the subcarrier bandwidth, which is 15 kHz, see Figure Resource Element The smallest resource unit handled in LTE consists of the combination of: • The smallest time domain unit, one OFDM symbol • The smallest frequency domain unit, one subcarrier This unit is called...

A transmitted OFDMA signal can be carried by a number of parallel subcarriers. Each LTE subcarrier is 15 kHz. Twelve subcarriers (180 kHz) are grouped into a resource block. The downlink has an unused central subcarrier. Depending on the total deployed bandwidth, LTE supports a varying number of resource blocks. The following illustration shows resource block definition: A resource block is limited in both the frequency and time domains. One resource block is 12 subcarriers during one slot (0.5 ms). In the downlink, the time-frequency plane of OFDMA structure is used to its full potential. The scheduler can allocate resource blocks anywhere, even non-contiguously.  A variant of OFDMA is used in the uplink. This variant requires the scheduled bandwidth to be contiguous, forming in effect a single carrier. The method, called SC-FDMA, can be considered a separate multiple access method. A user is scheduled every Transmission Time Interval (TTI) of 1 ms, indicati...

Five UE categories have been specified by 3GPP in User Equipment (UE) radio access capabilities, 3GPP TS 36.306 . Each category is specified by a number of downlink and uplink physical layer parameter values listed in fig.     3GPP has in User Equipment (UE) radio transmission and reception, 3GPP TS 36.101 specified one power class, UE power class 3, that has a maximum output power of 23 dBm.

The LTE RAN consists of these parts: §    RBS §    OSS-RC RAN components §    Interconnecting IP transport network The following figure shows the logical structure of a single RBS in LTE RAN and how it interconnects with other components of LTE RAN: Logically, each RBS is comprised of sectors, a digital unit, and a support system. Each sector is connected to one or a number of antenna unit groups. Connection to other RAN and core network elements is provided by the IP transport infrastructure. In some implementations, common elements of the RBS can be shared with other technologies such as WCDMA or GSM. Refer to RBS Configurations for further details. The following list defines terms used to describe parts of the LTE RBS: Antenna Unit Group An Antenna Unit Group (AUG) is the logical structure that includes all details of an antenna and associated equipment. This includes the antenna, and an...

Single Cell Function test SCFT is for verifying whether individual BTS works well or not, by making a single cell function test of BTS hardware and software. Essential items to be tested are as follows: 1) BTS Transmitter Output Measurement Test 2) Initial parameter establishment (Pilot PN/System ID/Site ID/Frequency, Neighbor List) 3) Call Origination and Termination Test 4) Softer Handoff Test/Antenna installation check (Direction, Tilt, Transmission Line) 5) Single Cell Coverage Test 6) Noise Floor Test 7) Parameter check.