Tx Power Recommendation

Tx Power Recommendation

Tx Power Recommendation

Transmit Power Recommendation for TDD LTE Base Station

TABLE OF CONTENTS1Introduction21.1TDD Frame structure22WPC BWA Allocation Letter33TDD LTE BTS Transmit Power43.1BTS Transmit Power Ratio TDD Config #2 (3:1) and special sub frame (10:2:2)43.1.12T2R @ 10 W per Port53.1.22T2R @ 20 W per Port53.1.34T4R @ 10 W per Port63.1.44T4R @ 20 W per Port63.2BTS Transmit Power Ratio TDD Config #1 (2:2) and special sub frame (10:2:2)73.2.12T2R @ 10 W per Port73.2.22T2R @ 20 W per Port83.2.34T4R @ 10 W per Port83.2.44T4R @ 20 W per Port94Recommendation9

1 Introduction 1.1 TDD Frame structure

The LTE-TDD frame format defined in 3GPP is Type 2 1 radio frame (10ms) = 2 half-frames (5ms) , 1 half-frame = 4 sub frames (1ms)+ 1 special sub frame (1ms) The special sub frame contains 3 timeslots: DwPTS, GP, and UpPTS The lengths of DwPTS and UpPTS are configurable

ConfigurationSwitch-point periodicitySub frame number

0123456789

15 msDSUUDDSUUD

25 msDSUDDDSUDD

D: - Down Link Subframe (Used for downlink transmission)U: - Uplink Subframe (Used for uplink transmission)S: - Special Subframe (Used between DL to UL transmission)Currently in our TDD LTE network for some of the circles are using TDD Config #1 and others TDD Config #2, circles with deployment in TDD Config#1 are planned to be shifted to TDD Config #2 in near futureTDD Config #1In this configuration in a frame of 5ms, ENodeB transmits in 2 dedicated sub frame for DL and partially in the special sub frame in case it is used for DL. Each of these sub frame accounting for 1ms eachTDD Config #2In this configuration in a frame of 5ms, EnodeB transmits in 3 dedicated sub frame for DL and partially in the special sub frame in case it is used for DL. Each of these sub frames accounting for 1ms each

2 WPC BWA Allocation Letter

Emission type is 20M0G7WEmission Type Details

20M020 MHz Band

GPhase Modulated Signal

7Two or More channels

WAll types of services

With the above mentioned letter, it is not clear that the maximum transmit power of 43 dBm as mentioned above is per BTS port or BTS sector

3 TDD LTE BTS Transmit Power

In TDD LTE, BTS transmit 74% (config -2) or 54% (config -1) of the frame time (10 ms) depending on the TDD configuration therefore average power over the TDD frame time is always lower than peak transmit power.TD LTE BS peak power per subframe can only be measured using Spectrum Analyzer, which measures the power transmitted by the base station over a period of 1ms (subframe) after synchronization with GPS or BTS clock

TX PWR Measured using SA during no Load TX PWR Measured using SA with 100% Load

In Field, when regular power meter or site master is used to measure the TDD LTE BS transmit power per port, it actually measure average power over multiple TDD frames, hence total power averaged over frame is always lower as described in the subsequent sections.3.1 BTS Transmit Power Ratio TDD Config #2 (3:1) and special sub frame (10:2:2)

TDD ConfigurationSwitch-point periodicitySub frame number

0123456789

25 msDSUDDDSUDD

In TDD config 2, 3 Sub Frame used for DL transmission 1 Sub frame used for UL transmission Each sub frame has 14 OFDMA symbol divided into 1 ms Special sub frame configured as (10:2:2) 10 OFDMA symbols for DwPTS(Used for DL Tx) 2 OFDMA symbols for Gp (Used guard between DL UL transmission) 2 OFDMA symbol for UpPTS(Used for UL Tx)

Percentage time EnodeB would be transmitting in a 5ms frame3 DL Subframe + 10 OFDMA symbol in SSF = 3 ms + (1 ms *10/14) = 3.71 ms Hence in TDD LTE Config 2 BTS, Average Power Output ratio over 5ms frame = 3.71/5 = 74.29%3.1.1 2T2R @ 10 W per Port

2T2R @ 10W Per Port

AntennaFrequencyLoadingPeak Power Transmitted over 1 DL TDD SubframeAverage Power Transmitted over 5ms TDD frame

02300 MHz0%3028.7

50%36.5535.8

100%39.8938.7

12300 MHz0%3028.7

50%36.5535.8

100%39.8938.7

Total2300 MHz0%3331.7

50%39.5538.8

100%42.8941.7

3.1.2 2T2R @ 20 W per Port

2T2R @ 20W Per Port

AntennaFrequencyLoadingPeak Power Transmitted over 1 DL TDD SubframeAverage Power Transmitted over 5ms TDD frame

02300 MHz0%3331.7

50%39.5538.8

100%42.8941.7

12300 MHz0%3331.7

50%39.5538.8

100%42.8941.7

Total2300 MHz0%3634.7

50%42.5541.8

100%45.8944.7

3.1.3 4T4R @ 10 W per Port

4T4R @ 10W Per Port

AntennaFrequencyLoadingPeak Power Transmitted over 1 DL TDD SubframeAverage Power Transmitted over 5ms TDD frame

02300 MHz0%3028.7

50%36.8435.8

100%39.8938.7

12300 MHz0%3028.7

50%36.8435.8

100%39.8938.7

22300 MHz0%3028.7

50%36.8435.8

100%39.8938.7

32300 MHz0%3028.7

50%36.8435.8

100%39.8938.7

Total2300 MHz0%3634.7

50%42.8441.8

100%45.8944.7

3.1.4 4T4R @ 20 W per Port

4T4R @ 20W Per Port

AntennaFrequencyLoadingPeak Power Transmitted over 1 DL TDD SubframeAverage Power Transmitted over 5ms TDD frame

02300 MHz0%3331.7

50%39.8438.8

100%42.8941.7

12300 MHz0%3331.7

50%39.8438.8

100%42.8941.7

22300 MHz0%3331.7

50%39.8438.8

100%42.8941.7

32300 MHz0%3331.7

50%39.8438.8

100%42.8941.7

Total2300 MHz0%3937.7

50%45.8444.8

100%48.8947.7

3.2 BTS Transmit Power Ratio TDD Config #1 (2:2) and special sub frame (10:2:2)

TDD ConfigurationSwitch-point periodicitySub frame number

0123456789

15 msDSUUDDSUUD

In TDD config 1, 2 Sub Frame used for DL transmission 2 Sub frame used for UL transmission Each sub frame has 14 OFDMA symbol divided into 1 ms Special sub frame configured as (10:2:2) 10 OFDMA symbols for DwPTS(Used for DL Tx) 2 OFDMA symbols for Gp (Used guard between DL UL transmission) 2 OFDMA symbol for UpPTS(Used for UL Tx)

Percentage time EnodeB would be transmitting in a 5ms frame2 DL Subframe + 10 OFDMA symbol in SSF = 2 ms + (1 ms *10/14) = 2.71 ms

Hence in TDD LTE Config 2 BTS, Average Power Output ratio over 5ms =2.71/5 = 54.29%3.2.1 2T2R @ 10 W per Port

2T2R @ 10W Per Port

AntennaFrequencyLoadingPeak Power Transmitted over 1 DL TDD SubframeAverage Power Transmitted over 5ms TDD frame

02300 MHz0%3028.7

50%36.5534.3

100%39.8937.3

12300 MHz0%3028.7

50%36.5534.3

100%39.8937.3

Total2300 MHz0%3331.7

50%39.5537.3

100%42.8940.3

3.2.2 2T2R @ 20 W per Port

2T2R @ 20W Per Port

AntennaFrequencyLoadingPeak Power Transmitted over 1 DL TDD SubframeAverage Power Transmitted over 5ms TDD frame

02300 MHz0%3331.7

50%39.5537.3

100%42.8940.3

12300 MHz0%3331.7

50%39.5537.3

100%42.8940.3

Total2300 MHz0%3634.7

50%42.5540.3

100%45.8943.3

3.2.3 4T4R @ 10 W per Port

4T4R @ 10W Per Port

AntennaFrequencyLoadingPeak Power Transmitted over 1 DL TDD SubframeAverage Power Transmitted over 5ms TDD frame

02300 MHz0%3028.7

50%36.5534.3

100%39.8937.3

12300 MHz0%3028.7

50%36.5534.3

100%39.8937.3

22300 MHz0%3028.7

50%36.5534.3

100%39.8937.3

32300 MHz0%3028.7

50%36.5534.3

100%39.8937.3

Total2300 MHz0%3634.7

50%42.5540.3

100%45.8943.3

3.2.4 4T4R @ 20 W per Port4T4R @ 20W Per Port

AntennaFrequencyLoadingPeak Power Transmitted over 1 DL TDD SubframeAverage Power Transmitted over 5ms TDD frame

02300 MHz0%3331.7

50%39.5537.3

100%42.8940.3

12300 MHz0%3331.7

50%39.5537.3

100%42.8940.3

22300 MHz0%3331.7

50%39.5537.3

100%42.8940.3

32300 MHz0%3331.7

50%39.5537.3

100%42.8940.3

Total2300 MHz0%3937.7

50%45.5543.3

100%48.8946.3

4 Recommendation

There is no clear guideline from WPC that 20 watt BTS power limitation is per BTS port or maximum sector output power. Assuming power limitation is per sector, even though, BS transmits under limits upto 50% loading as evident from the tables above. In config- 1 BTS transmits 54% of the frame time and 74% in config-2. Site master or power meter averages out power over frame time hence, power observed is much lower than peak power transmitted.Therefore, it is recommended to use 20 watt per port for 2T2R BS configuration and 10 watt per port for 4T4R BS configuration till the time BS is loaded upto 50%.

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One radio frame =10 ms

One half frame =5 ms

# 0

# 2

# 3

# 4

# 5

# 7

# 8

# 9

DwPTS

UpPTS

GP

1 ms

DwPTS

UpPTS

GP