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Emergence of powerful business modelsfor fixed wireless data

Dr Andre FourieCEO, Poynting Antennas

Overview

• Revenue generating capacity of LTE base station limited by:– Spectrum– Efficient use thereof

• E.g., spectral cost of delivering:– 1 Mbit/s for 1 minute– 10 Mbit/s for 1 minute

• Must maximise use of spectrum

Effect of outdoor antennas

  Data rate attained (up/down) (Mbit/s)

LTE device Using internal antennas

LPDA-A0092 (dual polarised)

XPOL-A0001

XPOL-A0002

Huawei B593

2.47/1.72 11.2/8.95 10.5/6.83 9.83/8.36

Huawei E3276

2.19/0.75 11.8/4.56 10.3/4.47 12/7.56

Effect of outdoor antennas

• 4-5 times improvement in download speeds

• Commensurate increase in revenue generation capability

Why are outdoor antennas better?• Higher gain antenna

• Ability to filter out noise (cf omni)

• Outdoor vs indoor environment

Characteristics of indoor environment• Rayleigh fading

Characteristics of outdoor environment (with LOS)Additive white Gaussian noise

Characteristics of general outdoor environment• Characteristics lie somewhere

between Rayleigh and AWGN fading

• Ricean distribution

• K-factor; defining ratio between predominant signal and multipath components

Comparison

Comparison

• Assume use 64QM 5/6 outdoors

• SNRoutdoor = 18 dB

• SNRindoor = 34 dB

• => move antenna outdoors gains 16 dB signal improvement

• Gain of outdoor antenna improves further

FCC: using outdoor antennas

• Spectral efficiency improved more than 75%

FCC: quote

• Figures quoted by the FCC indicate that if a CPE with an omni antenna experiences a data rate of 3 Mbit/s, then that same user will average 9 Mbit/s by converting to an outdoor directional antenna.

Our experience reiterated

  Data rate attained (up/down) (Mbit/s)

LTE device Using internal antennas

LPDA-A0092 (dual polarised)

XPOL-A0001

XPOL-A0002

Huawei B593

2.47/1.72 11.2/8.95 10.5/6.83 9.83/8.36

Huawei E3276

2.19/0.75 11.8/4.56 10.3/4.47 12/7.56

What have we established

• Established that outdoor directional antennas have a large impact on LTE performance

• Reasons for why this is the case have been given

• For business purposes; need to establish the system capacity of an LTE cell

Practical LTE capacity

• Advertised that 20 MHz LTE link achieve 300 Mbit/s

• Vodacom recently claimed 380 Mbit/s on 2x20 MHz LTE

• Is this practically what one expects?

WiMAX carrier capacity : Korowajczuk

Carrier overhead Percentage

Guard bands 18

Pilot DL and UL 25

Cyclic prefix 13

TDD partition 5

TDD gap 3

OFDMA preamble and mapping 10

Total for support 72

Available for data 28

Additional overhead

Data overhead Minimum (%)

Maximum (%)

Coding 17 50

MAC overhead 3 5

HARQ 10 15

Total 30 70

Available for data 20 8

Summary: WiMAX capacity

• Only 8% to 20% of the carrier capacity is available for the actual data to be transmitted in WiMAX.

• A similar situation is to be found for LTE

LTE capacity (no overhead)NO OVERHEAD Normal cyclic

prefixChannel bandwidth (MHz) 10 20Transmission bandwidth (MHz) 9 18Bandwidth efficiency (%) 90 90FFT size 1024 2048Number of used sub-carriers 600 1200Number of sub-carrier groups 50 100Number of resource blocks / frame 1000 2000Number of resource elements / frame 84 168Number of resource elements / second 8.4 16.8Minimum throughput with no overhead and QPSK (Mbit/s)

16.8 33.6

Maximum throughput with no overhead and 64QAM (Mbit/s)

50.4 100.8

Comment on published LTE performance• With 20 MHz spectrum achieve 100.8

Mbit/s with no MIMO

• Assume 4x4 MIMO 403.2 Mbit/s

• Vodacom achieved 380 Mbit/s but the data contained no overhead and no error correction data

Include overheadINCLUDING OVERHEAD Normal cyclic prefix

Channel bandwidth (MHz) 10 20

Number of sub-carrier groups 50 100

Total resource elements / frame (thousand) 84 168

Reference signals RE / frame (thousand) 2.0 4.0

PSS RE / frame (thousand) 4.2 8.4

SSS RE / frame (thousand) 4.2 8.4

PBCH RE / frame (thousand) 4.0 8.0

PDCCH RE / frame (thousand) 19.0 38.0

PDSCH RE / frame (thousand) 50.6 101.2

Channel coding overhead (turbo code at 1/3) % 66 66

Channel coding overhead (turbo code at 2/3) % 33 33

Percentage of RE available for data (worst case) 20 20

Percentage of RE available for data (best case) 40 40

Minimum throughput (QPSK) with overhead (Mbit/s) 3.44 6.88

Maximum throughput (64QAM) with overhead (Mbit/s) 20.34 40.68

Include overhead and inefficiencies

INCLUDING OVERHEAD AND INEFFICIENCIES

Normal cyclic prefix

Channel bandwidth (MHz) 10 20

RB allocation inefficiency (%) 80 80

RB sub-utilisation (%) 78 78

ARQ and H_ARQ (%) 88 88

Minimum throughput (QPSK) with overhead and inefficiency (Mbit/s)

1.89 3.78

Maximum throughput (64QAM) with overhead and inefficiency (Mbit/s)

11.17 22.34

Include MIMO

UPLINK INCLUDING OVERHEAD AND INEFFICIENCIES AND MIMO

Normal cyclic prefix

Channel bandwidth (MHz) 10 20

Minimum throughput (QPSK) with overhead and inefficiency (Mbit/s)

1.89 3.78

Maximum throughput (64QAM) with overhead and inefficiency (Mbit/s)

21.2 42.5

Summary of LTE performance

• 380 Mbit/s is possible as long as no overhead or error correction is required – one user and a highly specialised application

• The total capacity is closer to 40 Mbit/s assuming excellent signal quality to all users! In reality capacity will be less than this!

The business case for outdoor antennas• We have established:

Parameter Value

LTE billable spectrum 4-42.5 Mbit/s

Improvement in data speeds due to external directional antennas rather than internal omni antennas

3-5 times

A simplified user distribution

The financial effect of outdoor antennas

Parameter ValueAvailable bandwidth (MHz) 20MIMO efficiency 90%Price per MBit (R) 0.01

Load (8am-5pm) 90% 9 hoursLoad (5pm-10pm) 50% 5 hoursLoad (10pm-8am) 25% 10 hours

QPSK (Mbit/s) 3.7864QAM (Mbit/s) 42.5

Minimum revenue per annum ZAR 1,236,266.39Maximum revenue per day per annum ZAR 13,899,820.50

Estimated revenue assuming omni antennas ZAR 3,422,135.81Estimated revenue assuming directional antennas ZAR 9,496,357.37

Number of users on base station 1000Cost of antenna with installation ZAR 2,000.00Total cost of external antennas ZAR 2,000,000.00

Conclusion

• The use of outdoor direction antennas improves the spectral use of the base station

• Improving the spectral use is financially beneficial