LTE Link Budget Comparison

1. Introduction

The tables below show a link budget comparison between LTE, GSM and UMTS HSPA.

2. Uplink Budget Comparison

The following table based on [1],[2] compares the uplink budget for LTE, HSPA and GSM

 

RAN Technology

GSM

HSPA

LTE

Data rate (kbps)

12.2

64

64

Transmitter – UE

 

 

 

a

Max. TX power (dBm)

33

23

23

b

TX antenna gain (dBi)

0

0

0

c

Body loss (dB)

3

0

0

d

EIRP (dBm)

30

23

23

 

 

 

 

 

Receiver – BTS/Node B/eNode B

 

 

 

e

Node B noise figure (dB)

-

2

2

f

Thermal noise (dBm)

-

-108.2

-118.4

g

Receiver noise floor (dBm)

-

-106.2

-116.4

h

SINR (dB)

-

-17.3

-7

i

Receiver sensitivity (dBm)

-114

-123.4

-123.4

j

Interference Margin (dB)

0

3

1

k

Cable Loss (dB)

0

0

0

l

RX antenna gain (dBi)

18

18

18

m

Fast fade margin (dB)

0

1.8

0

n

Soft handover gain (dB)

0

2

0

 

 

 

 

 

Maximum path loss

162

161.6

163.4

 

The uplink link budget has some differences in comparison to HSPA: specifically the smaller interference margin, no macro diversity gain (Soft handover gain) and no fast fading margin. As can be seen from the table above the link budget was calculated for 64 kbps uplink, which is cannot be classified as a high enough data rate for true broadband service. To guarantee higher data rates for LTE, a low frequency deployment may be required in addition to additional sites, active antenna solutions or local area solutions.

2. Downlink Budget Comparison

The following table based on [1],[2] compares the downlink budget for LTE, HSPA and GSM

 

RAN Technology

GSM

HSPA

LTE

Data rate (kbps)

12.2

1024

1024

Transmitter – BTS/Node B, eNode B

 

 

 

a

Max. TX power (dBm)

44.5

46

46

b

TX antenna gain (dBi)

18

18

18

c

Cable loss (dB)

2

2

2

d

EIRP (dBm)

60.5

62

62

 

 

 

 

 

Receiver – UE

 

 

 

e

UE noise figure (dB)

-

7

7

f

Thermal noise (dBm)

-119.7

-108.2

-104.5

g

Receiver noise floor (dBm)

-

-101.2

-97.5

h

SINR (dB)

-

-5.2

-9

i

Receiver sensitivity (dBm)

-104

-106.4

-106.4

j

Interference Margin (dB)

0

4

4

k

Control channel overhead (%)

0

20

20

l

RX antenna gain (dBi)

0

0

0

m

Body loss (dB)

3

0

0

 

 

 

 

 

Maximum path loss

161.5

163.4

163.5

 

 The LTE link budget in downlink has several similarities with HSPA and the maximum path loss is similar. The link budgets show that LTE can be deployed using existing GSM and HSPA sites assuming that the same frequency is used for LTE as for GSM and HSPA. LTE itself does not provide any major boost in the coverage. That is because the transmission power levels and the RF noise figures are also similar in GSM and HSPA technologies, and the link performance at low data rates is not much different in LTE than in HSPA.


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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