LTE DRIVE TEST PARAMETERS

RSRP :- Reference signal receive power.

•      RSRP (dBm) = RSSI (dBm) -10*log (12*N)

where RSSI = Received Signal Strength Indicator

             N: number of RBs across the RSSI is measured and depends on the BW

Significance :
RSRP is the most basic of the UE physical layer measurements and is the linear average power (in watts) of the downlink reference signals (RS) across the channel bandwidth for the Resource elements that carry cell specific Reference Signals. 

Knowledge of absolute RSRP provides the UE with essential information about the strength of cells from which path loss can be calculated and used in the algorithms for determining the optimum power settings for operating the network. Reference signal receive power is used both in idle and connected states

Range :-  -44 to -140 dBm

•      RSRP term is used for coverage same as RSCP in 3G

RSRQ :Reference signal receive quality

RSRQ = RSRP / (RSSI / N)

N is the number of resource blocks over which the RSSI is measured

RSSI is wide band power, including intra cell power, interference and noise.

Significance :- 
 It provides the Indication of Signal Quality . Measuring RSRQ becomes particularly important near the cell edge when  decisions need to be made, regardless of absolute RSRP, to perform a handover to the next cell. Reference signal receive quality is used only during connected states

Range :-  -3 to -19.5 dB

•      RSRQ term is used for Quality same as Ec/No in 3G.

•      SINR :- Signal to Noise Ratio.

SINR = S / I + N

             

               S -- Average Received Signal Power

                I  --  Average Interference power

                N --  Noise Power

Significance  : Is a way to measure the Quality of LTE Wireless Connections. As the energy of signal fades with distance i.e Path Loss due to environmental parameters ( e.g. background noise , interfering strength of other simultaneous transmission)

•      RSSI :- Received Signal Strength Indicator.

•

•    RSSI = wideband power = noise + serving cell power + interference power

•     RSSI=12*N*RSRP

•     RSSI per resource block is measured over 12 resource elements.

N: number of RBs across the RSSI is measured and depends on the BW

Based on the above:

                                
RSRP (dBm) = RSSI (dBm) -10*log (12*N)

•      Significance :– 
       Is the parameter represents the entire received power including the wanted power from the serving cell as well as all the co channel power & other sources of noise

•     CQI :- Channel Quality Indicator

•     Range :- 1 to 15

                 

        Significance:
       CQI is a measurement of the communication quality of wireless channels i.e. it indicates the downlink mobile radio channel quality as experienced by the UE .CQI can be a value representing a measure of channel quality for a given channel. Typically, a high value CQI is indicative of a channel with high quality and vice versa.

•      CQI is measured in the Dedicated mode only.

•

•    CQI depends on the RF conditions.

•

•    Better the CQI better the throughput will get and vice versa.

•    PCI :- Physical Cell Id

      Range :- 0 to 503

•    Significance - PCI used to identify the cell & is used to transmit the data

•

•       PCI = PSS + 3*SSS

               PSS is Primary Synchronization Signal ( Identifies Cell Id  ).

               PSS value can be 0, 1 & 2

               SSS is Secondary Synchronization Signal ( identifies Cell Id

               group).

               SSS value can be 0 to 167.

•    BLER :- Block Error Rate

•    Block Error Ratio is defined as the ratio of the number of erroneous   blocks received to the total number of blocks transmitted

•

     Significance - 
        A simple method by which a UE can choose an appropriate CQI value could be based on a set of Block Error Rate (BLER) thresholds . The UE would report the CQI value corresponding to the Modulation Coding Schemes that ensures  BLER ≤ 10% based on the measured received signal quality

•

•    BLER is Calculated using Cyclic Redundancy error Checking method

      High BLER leads to loss of Peak rates & efficiency

      BLER  threshold should be low i.e. ≤ 10%

  

     

DDownlink Throughput

-I    n E-UTRAN  may use a maximum of 2 Tx antennas at the ENodeB and 

       2 Rx antennas at the UE ( MIMO ).

   Significance - Target for averaged user throughput per MHz, 3 to 4 times

   Release 6 HSDPA i.e Higher user throughput as compared to 3G ( Over 300 Mbps downlink as compared to 14 Mbps in UMTS)

-    The supported user throughput should scale with the spectrum

      bandwidth.

    Uplink Throughput

-I  n E-UTRAN uses  a maximum of a single Tx antenna at the UE and 2 Rx

    antennas at the E Node B.

 -  Greater user throughput should be achievable using multiple Tx

     antennas at the UE ( MIMO )

.

-  Significance- 
    Target for averaged user throughput per MHz, 2 to 3 times Release 6 Enhanced Uplink i.e Higher user throughput as compared to 3G (Over 50 Mbps Uplink as compared to 5.76 Mbps in UMTS).The user throughput should scale with the spectrum bandwidth provided that the maximum transmit power is also scaled.