Throughput Calculation Based on Worst Case Between C and C/I

Throughput Calculation Based on Interpolation Between C/N and C/(I+N)

For the coding scheme cs_C/N determined above, the TP = f(C) graph is internally converted to TP = f(C/N) graph. A throughput value, TP_C/N, corresponding to the C/(I+N) is determined from the TP = f(C/N) graph.

For the coding scheme cs_C/(I+N) determined above, the TP = f(C/I) graph is internally converted to TP = f(C/(I+N)) graph.

A throughput value, TP_C/(I+N), corresponding to the C/(I+N) is determined from the TP = f(C/(I+N)) graph.

The final throughput is computed by interpolating between the throughput values obtained from these two graphs. The throughput interpolation method consists in interpolating TP_C/N and TP_C/(I+N) according to the respective weights of I and N values.

The resulting throughput TP is given by:

Where , pN is the thermal noise power (value in Watts), and p(I+N) is the interferences + thermal noise power (value in Watts).

5.3.2 Coding Scheme Selection and Throughput Calculation With Ideal Link Adaptation

5.3.2.1 Calculations Based on C

Throughput Calculation

For the received signal level, and coding schemes whose reception thresholds are lower than the received signal level, Atoll determines the highest throughput from the graphs available in the GPRS/EDGE configuration.

Coding Scheme Selection

The selected coding scheme, cs, is the one corresponding to the highest throughput calculated above.

If there are more than one coding schemes providing the highest throughput at the pixel, the selected coding scheme, cs, is the one with the lowest coding scheme number from the lowest priority coding scheme list.

5.3.2.2 Calculations Based on C/I

Throughput Calculation Based on Worst Case Between C and C/I

TP = Min TP _CTP_{C I}_

For the received C/I, and coding schemes whose C/I thresholds are lower than the received C/I, Atoll determines the highest throughput from the graphs available in the GPRS/EDGE configuration.

The resulting throughput TP is the lower of the two values, TP_C and TP_C/I.

Coding Scheme Selection

The selected coding scheme, cs, is the one corresponding to the lower of the two highest throughputs calculated above.

If there are more than one coding schemes providing the highest throughputs at the pixel, the selected coding scheme, cs, is the one with the lowest coding scheme number from the lowest priority coding scheme list.

5.3.2.3 Calculations Based on C/(I+N)

Throughput Calculation Based on Interpolation Between C/N and C/(I+N)

Atoll internally converts the TP = f(C) graphs into TP = f(C/N) graphs. For the received C/(I+N), and coding schemes whose C/(I+N) thresholds are lower than the received C/(I+N), Atoll determines the highest throughput from the TP = f(C/

N) graphs available in the GPRS/EDGE configuration.

Atoll internally converts the TP = f(C/I) graphs into TP = f(C/(I+N)) graphs. For the received C/(I+N), and coding schemes whose C/(I+N) thresholds are lower than the received C/(I+N), Atoll determines the highest throughput from the TP = f(C/

(I+N)) graphs available in the GPRS/EDGE configuration.

The resulting throughput TP is given by:

Where , pN is the thermal noise power (value in Watts), and p(I+N) is the interferences + thermal noise power (value in Watts).

Coding Scheme Selection

The selected coding scheme, cs, is the one corresponding to the higher of the two highest throughputs calculated above.

If there are more than one coding schemes providing the highest throughputs at the pixel, the selected coding scheme, cs, is the one with the highest coding scheme number from the highest priority coding scheme list.

5.3.3 Application Throughput Calculation

Application throughput is calculated from the RLC/MAC throughput as follows:

Where is the RLC/MAC throughput, and and are the throughput offset (kbps) and the throughput scaling factor (%) defined for the selected service.

TP_C = Highest TP=f C  =P_rec^TxiTRX P– _Backoff^Txi TRX CS

TPApplication TP_{RLC MAC}_ SF

100---–TP_Offset



TP_{RLC MAC}_ TP_Offset SF

5.3.4 BLER Calculation

Block error rate is calculated as follows:

Where TP is the throughput per timeslot calculated for a pixel and TP_MAX is the maximum throughput per timeslot read from the GPRS/EDGE configuration used for the calculations.

5.3.5 GPRS/EDGE Coverage Predictions

Two GPRS/EDGE coverage predictions are available:

• GPRS/EDGE Coding Schemes: Shows the areas where various coding schemes are available.

• Packet Throughput and Quality: Shows the throughputs corresponding to the coding schemes available.

For each TBC transmitter, Txi, Atoll calculates the selected parameter on each pixel inside the Txi calculation area. In other words, each pixel inside the Txi calculation area is considered a probe (non-interfering) receiver.

Coverage prediction parameters to be set are:

• The coverage conditions in order to determine the service area of each TBC transmitter,

• The interference conditions to meet for a pixel to be covered, and

• The display settings to select the displayed parameter and its shading levels.

The thermal noise (N = -121 dBm, by default) is used in the calculations if the coverage prediction is based on C/(I+N).

This value can be modified by the user.

5.3.5.1 Service Area Determination

Atoll uses parameters entered in the Condition tab of the coverage prediction properties dialogue to determine the areas where coverage will be displayed.

We can distinguish eight cases as below. Let us assume that:

• Each transmitter, Txi, belongs to a Hierarchical Cell Structure (HCS) layer, k, with a defined priority and a defined reception threshold.

• Each transmitter, Txi, is GPRS/EDGE-capable.

• No max range is set.

5.3.5.1.1 All Servers

The service area of Txi corresponds to the pixels where:

5.3.5.1.2 Best Signal Level and a Margin

The service area of Txi corresponds to the pixels where:

And

Where M is the specified margin (dB). The Best function considers the highest value from a list of values.

• If M = 0 dB, Atoll considers pixels where the received signal level from Txi is the highest.

• If M = 2 dB, Atoll considers pixels where the received signal level from Txi is either the highest or within a 2 dB margin from the highest.

• If M = -2 dB, Atoll considers pixels where the received signal level from Txi is 2 dB higher than the signal levels from transmitters which are 2^nd best servers.

5.3.5.1.3 Second Best Signal Level and a Margin

The service area of Txi corresponds to the pixels where:

And

Where M is the specified margin (dB). The 2^nd Best function considers the second highest value from a list of values.

• If M = 0 dB, Atoll considers pixels where the received signal level from Txi is the second highest.

BLER

TP TP_MAX

--- If TP TP_MAX 0 If TP TP_MAX







SubcellReceptionThresholdP_rec^Txi tt

P_rec^Txi tt Best

ji P_rec^Txj tt M–



SubcellReceptionThresholdP_rec^Txi tt

P_rec^Txi tt 2^ndBest

ji P_rec^Txj tt M–



• If M = 2 dB, Atoll considers pixels where the received signal level from Txi is either the second highest or within a 2 dB margin from the second highest.

• If M = -2 dB, Atoll considers pixels where the received signal level from Txi is 2 dB higher than the signal levels from transmitters which are 3^rd best servers.

5.3.5.1.4 Best Signal Level per HCS Layer and a Margin

For each HCS layer, k, the service area of Txi corresponds to the pixels where:

And

Where M is the specified margin (dB). The Best function considers the highest value from a list of values.

• If M = 0 dB, Atoll considers pixels where the received signal level from Txi is the highest.

• If M = 2 dB, Atoll considers pixels where the received signal level from Txi is either the highest or within a 2 dB margin from the highest.

• If M = -2 dB, Atoll considers pixels where the received signal level from Txi is 2 dB higher than the signal levels from transmitters which are 2^nd best servers.

5.3.5.1.5 Second Best Signal Level per HCS Layer and a Margin

For each HCS layer, k, the service area of Txi corresponds to the pixels where:

And

Where M is the specified margin (dB). The 2^nd Best function considers the second highest value from a list of values.

• If M = 0 dB, Atoll considers pixels where the received signal level from Txi is the second highest.

• If M = 2 dB, Atoll considers pixels where the received signal level from Txi is either the second highest or within a 2 dB margin from the second highest.

• If M = -2 dB, Atoll considers pixels where the received signal level from Txi is 2 dB higher than the signal levels from transmitters which are 3^rd best servers.

5.3.5.1.6 HCS Servers and a Margin

The service area of Txi corresponds to the pixels where:

And

And the received exceeds the reception threshold defined per HCS layer.

Where M is the specified margin (dB). The Best function considers the highest value from a list of values.

• If M = 0 dB, Atoll considers pixels where the received signal level from Txi is the highest.

• If M = 2 dB, Atoll considers pixels where the received signal level from Txi is either the highest or within a 2 dB margin from the highest.

• If M = -2 dB, Atoll considers pixels where the received signal level from Txi is 2 dB higher than the signal levels from transmitters which are 2^nd best servers.

5.3.5.1.7 Highest Priority HCS Server and a Margin

The service area of Txi corresponds to the pixels where:

And

And Txi belongs to the HCS layer with the highest priority. The highest priority is defined by the priority field (0: lowest).

And the received exceeds the reception threshold defined per HCS layer.

SubcellReceptionThresholdP_rec^Txi tt

P_rec^TxiBCCH Best

ji P_rec^TxjBCCH M–



SubcellReceptionThresholdP_rec^Txi tt

P_rec^TxiBCCH 2^ndBest

ji P_rec^TxjBCCH M–



SubcellReceptionThresholdP_rec^Txi tt

P_rec^TxiBCCH Best

ji P_rec^TxjBCCH M–



P_rec^Txi tt

SubcellReceptionThresholdP_rec^Txi tt

P_rec^TxiBCCH Best

ji P_rec^TxjBCCH M–



P_rec^Txi tt

Where M is the specified margin (dB). The Best function considers the highest value from a list of values.

• If M = 0 dB, Atoll considers pixels where the received signal level from Txi is the highest.

• If M = 2 dB, Atoll considers pixels where the received signal level from Txi is either the highest or within a 2 dB margin from the highest.

• If M = -2 dB, Atoll considers pixels where the received signal level from Txi is 2 dB higher than the signal levels from transmitters which are 2^nd best servers.

5.3.5.1.8 Best Idle Mode Reselection Criterion (C2)

Such type of coverage is useful:

• To compare idle and dedicated mode best servers for voice traffic

• Display the GPRS/EDGE best server map (based on GSM idle mode) The path loss criterion C1 used for cell selection and reselection is defined by:

The path loss criterion (GSM03.22) is satisfied if .

The reselection criterion C2 is used for cell reselection only and is defined by:

Where is the Cell Reselect Offset defined for the transmitter.

The service area of Txi corresponds to the pixels where:

And

The Best function considers the highest value from a list of values.

On each pixel, the transmitter with the highest C2 value is kept. It corresponds to the best server in idle mode. C2 is defined as an integer in the 3GPP specifications, therefore, the C2 values in the above calculations are rounded down to the nearest integer.

5.3.5.2 Coverage Display

5.3.5.2.1 Coverage Resolution

The resolution of the coverage prediction does not depend on the resolutions of the path loss matrices or the geographic data and can be defined separately for each coverage prediction. Coverage predictions are generated using a bilinear interpolation method from multi-resolution path loss matrices (similar to the one used to calculate site altitudes, see "Path Loss Calculations" on page 77 for more information).

5.3.5.2.2 Display Types

It is possible to display the coverage predictions with colours depending on criteria such as:

In document Atoll 2.8.3 RF Technical Reference Guide E2 (Page 144-148)