Selasa, 20 Maret 2012

RN Admission Control Parameter


Walau belum dapet kesempatan ngoptim 3G, ga ada salahnya gw pelajari parameter-parameternya. Berikut yang ingin gw pelajari hari ini :


RN Admission Control

aseDlAdm Cell parameter that defines the absolute admission limit for ASEs in the downlink.

aseUlAdm Cell parameter that defines the absolute admission limit for ASEs in the uplink.

compModeAdm Cell parameter that defines the absolute admission limit for the number of radio links in compressed mode in a cell.

dlCodeAdm Cell parameter that defines the absolute admission limit for downlink code usage.

pwrAdm Cell parameter that defines the absolute admission limit for downlink power utilization. It is relative to the min(maximumTransmissionPower, maxDlPowerCapability), it is expressed as a percentage and that is a percentage of min.( maximumTransmissionPower, maxDlPowerCapability).

hsdpaUsersAdm Cell parameter that defines the admission limit for the number of users assigned to the HS-DSCH. Applicable to admission requests related to RAB setup of an HSDPA service.

eulServingCellUsersAdm Cell parameter that defines the admission limit for the number of EUL users having the cell as serving cell.

eulNonServingCellUsersAdm Cell parameter that defines the admission limit for the number of EUL users having the cell as non-serving cell.

eulServingCellUsersAdmTti2 Cell parameter that defines the admission threshold for the number of 2 ms TTI E-DCH users having this cell as serving cell. Applicable at serving cell change, at RAB establishment and at re-configuration to EUL.

sf8Adm Cell parameter that defines the absolute admission limit for the number of radio links with spreading factor = 8 in downlink.

sf16Adm Cell parameter that defines the absolute admission limit for the number of radio links with spreading factor = 16 in downlink for which new non-guaranteed admission requests will continue to be allowed.

sf32Adm Cell parameter that defines the absolute admission limit for the number of radio links with spreading factor = 32 in downlink.

sf16gAdm Cell parameter that defines the maximum number of radio links with spreading factor = 16 in downlink for which new guaranteed admission requests will continue to be allowed. Reaching or exceeding this number of radio links (any service class) using downlink spreading factor = 16 will block setup/adding any more guaranteed service class radio links requiring additional downlink spreading factor = 16 in this cell.

sf4AdmUl Cell parameter that defines the absolute admission limit for the number of radio links with spreading factor = 4 in uplink (radio connection type PS384/HS).

sf8AdmUl Cell parameter that defines the absolute admission limit for the number of radio links with spreading factor = 8 in uplink.

sf16AdmUl Cell parameter that defines the absolute admission limit for the number of radio links with spreading factor = 16 in uplink.

sf8gAdmUl Cell parameter that defines the absolute admission limit for the number of radio links with spreading factor = 8 in uplink.

dlHwAdm Parameter that defines the admission limit for the downlink hardware usage in the cell group.

ulHwAdm Parameter that defines the admission limit for the uplink hardware usage in the cell group.

maxNumHsdpaUsers Parameter that limits the maximum allowed number of simultaneous HSDPA users per cell that can be served.

maxNumADchReservation The maximum number of A-DCH resources that may be configured in a baseband pool.

ulLicFractBbPool2 Parameter that defines the UL capacity of the second Base Band Pool in percentage of licensed UL capacity.

dlLicFractBbPool2 Parameter that defines the DL capacity of the second Base Band Pool in percentage of licensed DL capacity

plSessionsMax Parameter that defines the maximum number of ongoing MBMS sessions in one Preferred Layer cell.

nonPlSessionsMax Parameter that defines the maximum number of ongoing MBMS sessions in one non-Preferred Layer cell

Senin, 05 Maret 2012

LTE Radio Link Budgeting and RF Planning

The initial planning of any Radio Access Network begins with a Radio Link Budget. As the name suggests, a link budget is simply the accounting of all of the gains and losses from the transmitter, through the medium (free space, cable, waveguide, fiber, etc.) to the receiver in a telecommunication system. In this page, we will briefly discuss link budget calculations for LTE.

2. LTE Radio Link Budgeting

2.1. Typical Parameter Values

The link budget calculations estimate the maximum allowed signal attenuation g between the mobile and the base station antenna. The maximum path loss allows the maximum cell range to be estimated with a suitable propagation model. The cell range gives the number of base station sites required to cover the target geographical area.The following table shows typical (practical) parameter values used for doing an LTE Radio Link Budget.


Parameter

Typical Value

a

Base Station maximum transmission power. A typical value for macro cell base station is 20-69 W at the antenna connector.

43 – 48 dBm

b

Base Station Antenna Gain

Manufacturer Dependent

c

Cable loss between the base station antenna connector and the antenna. The cable loss value depends on the cable length, cable thickness and frequency band. Many installations today use RF heads where the power amplifiers are close to the antenna making the cable loss very small.

1 – 6 dB

d

Base Station EIRP, Calculated as A + B - C

e

UE RF noise figure. Depends on the frequency band. Duplex separation and on the allocated bandwidth.

6 – 11 dB

f

Terminal noise can be calculated as:

K (Boltzmann constant) x T (290K) x bandwidth”.

The bandwidth depends on bit rate, which defines the number of resource blocks. We assume 50 resource blocks, equal 9 MHz, transmission for 1 Mbps downlink.

-104.5 dBm for 50 resource blocks (9 MHz)

g

Calculated as E + F

h

Signal-to-noise ratio from link simulations or measurements. The value depends on the modulation and coding schemes, which again depend on the data rate and the number of resource blocks allocated.

-9 to -7 dB

i

Calculated as G + H

j

Interference margin accounts for the increase in the terminal noise level caused by the other cell. If we assume a minimum G-factor of -4 dB, that corresponds to 10*Log10(1+10^(4/10)) = 5.5 dB interference margin.

3 – 8 dB

k

Control channel overhead includes the overhead from reference signals,

PBCH, PDCCH and PHICH.

10 – 25 % =

0.4 – 1.0 dB

L

UE antenna gain.

Manufacturer Dependent

M

Body loss

Device Dependent


2.2. Uplink Budget

The table below shows an example LTE link budget for the uplink from [1], assuming a 64 kbps data rate and two resource block allocation (giving a 360 kHz transmission bandwidth). The UE terminal power is assumed to be 24 dBm (without any body loss for a data connection). It is assumed that the eNode B receiver has a noise figure of 2.0 dB, and the required Signal to Noise and Interference Ratio (SINR) has been taken from link level simulations performed in [1]. An interference margin of 2.0 dB is assumed. A cable loss of 2 dB is considered, which is compensated by assuming a masthead amplifier (MHA) that introduces a gain of 2.0 dB. An RX antenna gain of 18.0 is assumed considering a 3-sector macro-cell (with 65-degree antennas). In conclusion the maximum allowed path loss becomes 163.4 dB.

Uplink Link Budget for 64 kbps with dual-antenna receiver base station

Data rate (kbps)

64

Transmitter – UE

a

Max. TX power (dBm)

24.0

b

TX antenna gain (dBi)

0.0

c

Body loss (dB)

0.0

d

EIRP (dBm)

24.0 = a + b + c

Receiver – eNode B

e

Node B noise figure (dB)

2.0

f

Thermal noise (dBm)

-118.4 = k(Boltzmann) * T(290K)* B(360kHz)

g

Receiver noise floor (dBm)

-116.4 = e + f

h

SINR (dB)

-7.0 From Simulations performed in [1]

i

Receiver sensitivity (dBm)

-123.4 = g + h

j

Interference Margin (dB)

2.0

k

Cable Loss (dB)

2.0

l

RX antenna gain (dBi)

18.0

m

MHA gain (dB)

2.0

Maximum path loss

163.4 = d – i – j – k + l - m

The table below shows an example LTE link budget

2.3. Downlink Budget

The table below shows an example LTE link budget for the downlink from [1], assuming a 1 Mbps data rate (assuming antenna diversity) and 10 MHz bandwidth. The eNode B power is assumed to be 46 dBm, a value typical among most manufacturers. Again the SINR value is taken from link level simulations performed in [1]. A 3 dB interference margin and a 1 dB control channel overhead are assumed, and the maximum allowed path loss becomes 165.5 dB.

Downlink Link Budget for 1 Mbps with dual-antenna receiver terminal

Data rate (Mbps)

1

Transmitter – eNode B

a

HS-DSCH power (dBm)

46.0

b

TX antenna gain (dBi)

18.0

c

Cable loss (dB)

2.0

d

EIRP (dBm)

62.0 = a + b + c

Receiver – UE

e

UE noise figure (dB)

7.0

f

Thermal noise (dBm)

-104.5 = k(Boltzmann) * T(290K)* B(360kHz)

g

Receiver noise floor (dBm)

-97.5 = e + f

h

SINR (dB)

-10.0 From Simulations performed in [1]

i

Receiver sensitivity (dBm)

-107.5 = g + h

j

Interference Margin (dB)

3.0

k

Control Channel Overhead (dB)

1.0

l

RX antenna gain (dBi)

0.0

m

Body Loss (dB)

0.0

Maximum path loss

165.5 = d – i – j – k + l - m

The table below shows an example LTE link budget

2.4. Propagation (Path Loss) Models

A propagation model describes the average signal propagation, and it converts the maximum allowed propagation loss to the maximum cell range. It depends on:

  • Environment : urban, rural, dense urban, suburban, open, forest, sea…
  • Distance
  • Frequency
  • atmospheric conditions
  • Indoor/outdoor

Common examples include Free space, Walfish–Ikegami, Okumura–Hata, Longley–Rice, Lee and Young's models. The most commonly used model in urban environments is the Okumura-Hata model as described below:

For Urban Areas:
For Small and Medium-sized cities:
For Large cities:
where:

2.5. Mapping of Path Losses to Cell Sizes

For a path loss of 164 dB, based on the assumptions shown in the table below the following cell ranges can be attained with LTE. The cell range is shown for 900, 1800, 2100 and 2500 MHz frequency bands.

Assumptions

Okumura–Hata parameter

Urban Indoor

Suburban Indoor

Rural Indoor

Rural outdoor fixed

Base station antenna height (m)

30

50

80

80

Mobile antenna height (m)

1.5

1.5

1.5

5

Mobile antenna gain (dBi) 0

0.0

0.0

0.0

5.0

Slow fading standard deviation (dB)

8.0

8.0

8.0

8.0

Location probability (%)

95

95

95

95

Correction factor (dB)

0

-5

-15

-15

Indoor loss (dB)

20

15

0

0

Slow fading margin (dB)

8.8

8.8

8.8

8.8


Cell Size in Km

2.6. Comparison to Other Radio Access Technologies

In comparison to other Radio Access Technologies such as GSM or UMTS, LTE does not provide a significant increase in cell size or path loss measurements, however, the data rate (services) provided is much superior. In contrast to HSPA link budgets, the LTE Link budgets show up to roughly 2 dB higher values, which is mainly a result of low interference margins that can be achieved with orthogonal modulation. For a detailed comparison please refer to LTE Link Budget Comparison.

3. References

[1] H.Holma & A.Toskala, “WCDMA for UMTS: HSPA Evolution and LTE”, John Wiley & Sons, 2010

[2] H.Holma & A.Toskala, “LTE for UMTS: OFDMA and SC-FDMA based radio access”, John Wiley & Sons, 2009

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