SINR CQI RSRP RSSI RSRQ

SINR - Signal to Interference plus Noise Ratio

Signal to Interference plus Noise Ratio (SINR) is measured by UE on Resource Block (RB) basis.
UE computes SINR on each RB, converts it to CQI and reports it to eNodeB where it is used to select the most suitable MCS for user data transmission in particular RB. SINR value defines the MCS to be used for a RB i.e. the number of bits per modulation symbol to be sent i.e. throughput to be achieved for that particular RB as well as the number of RBs to be allocated by eNodeB to user. SINR can be defined as the ratio of the signal power to the summation of the average interference power from the other cells and the background noise.


CQI - Channel Quality Indicator

CQI is a quantized and scaled version of the experienced SINR. The process of adapting MCS depending on current channel conditions is termed as Link Adaptation. If the SINR is good, higher order MCS (e.g. 64QAM) can be selected implying that more bits per modulation symbol can be transmitted and higher throughput can be achieved. If the SINR is poor, lower order MCS (i.e. QPSK) should be selected implying fewer bits per symbol are transmitted which in turn results in lower throughput.


RSRP - Received Signal Received Power

Reference Signal Received Power (RSRP) is a cell-specific signal strength related metric that is used as an input for cell resection and handover decisions. For a particular cell, RSRP is defined as the average power (in Watts) of the Resource Elements (REs) that carry cell-specific Reference Signals (RSs) within the considered bandwidth.
RSRP measurement, normally expressed in dBm, is utilized mainly to make ranking among different candidate cells in accordance with their signal strength. Generally, the reference signals on the first antenna port are used to determine RSRP, however, the reference signals sent on the second port can also be used in addition to the RSs on the first port if UE can detect that they are being transmitted



RSRQ - .Reference Signal  Received Quality

Reference Signal Received Quality (RSRQ) measurement is a cell-specific signal quality metric. Similar to the RSRP measurement, this metric is used mainly to provide ranking among different candidate cells in accordance with their signal quality. This metric can be employed as an input in making cell reselection and handover decisions in scenarios (for example) in which the RSRP measurements are not sufficient to make reliable cell-reselection/handover decisions.
It is defined as
RSRQ = ( N.RSRP )/(LTE Carrier RSSI )
where, N is the number of Resource Blocks (RBs) of the LTE carrier Received Signal Strength Indicator (RSSI) measurement bandwidth.



RSSI - Received Signal Strength Indicator

Received Signal Strength Indicator (RSSI) is the linear average of the total received power observed only in OFDM symbols carrying reference symbols by UE from all sources, including co-channel non-serving and serving cells, adjacent channel interference and thermal noise, within the measurement bandwidth over N RBs. RSSI is used as an input to compute the LTE RSRQ measurement discussed above.


Reference- http://airccse.org/journal/jwmn/7415ijwmn09.pdf

RB RE Speed

Resource Element:
Covered by 1 sub carrier and one symbol period i.e 1 Symbol

Resource Block:
Covered by 12 Subcarriers and 6 or 7 symbols(Based on Cyclic prefix)

We can calculate the capacity if we know the Bandwidth allocated,Modulation scheme used and Cyclic Prefix type.
Consider 
Bandwidth Allocated = 5MHz
Modulation Scheme = QPSK(2 its per symbol)
Cyclic prefix used = Normal Cyclic Prefix (7 symbols in a slot)

Capacity = No of bits transferred in a sub frame / Duration of the Subframe(i.e 1milli sec)

Calculation No of Bits transferred in a Subframe

Total number of Resource block in a slot = Bandwidth / (Each subcarrier bandwidth * no of subcarriers in a Resource Block) 
Bandwidth = 5Mhz
Each sub carrier width = 15Khz
No of sub carriers in a Resource Block = 12 (As 12 Subcarrier is 1 Resource block )

Calculation of total no of resource blocks in 5MHz Bandwidth

so Resource block in one slot = 5 Mhz / (15 KHz *12 ) = 27.77 (But used RBs will be 25 for 5MHz bandwidth)
so Total Resource block in one subframe = 2 * Resource blocks in a slot = 50 RBs

Calculation of total no of symbols/Resource Elements in 5MHz Bandwidth
Total no of symbols / Resource Elements = 50 * no of symbols(REs) in a Resource block
No of symbols(REs) in a resource block = 12 subcarrier * 7 symbols = 84 symbols(REs)
Total symbols(REs ) in 50 Resource blocks = 50 * 84 = 4200 Resource Elements.

****Calculation of total no of bits sent in 5MHz Bandwidth in one subframe ****

In one symbol we can send no of bits at a time which depends on the modulation scheme (like BPSK,QPSK ,64QAM
BPSK - 1 bit,QPSK - 2 bit ,64 QAM - 6bits in a Symbol/ Resource elements
We will consider QPSK Scheme so in one symbol 2bits we can send.
So 1 Symbol = 2 bits.

So total no of Bits sent in a subframe = 2 * 4200 = 8400 bits.

So capacity = 8400 / 1ms = 8.4 MBPS

So capacity in 5MHz Bandwidth with QPSK Modulation with normal cyclic Prefix is 8.4MBPS.

if Modulation scheme is BPSK, 1 bits in a symbol = 1 * 4200 / 1ms = 4.2 MBPS
if Modulation scheme is 64QAM , 6 bits in a symbol = 6 * 4200 / 1ms = 25.2 MBPS.