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The Impact of Indoor Traffic on the Performance of WCDMA HSDPA Within Macro Cells

The Impact of Indoor Traffic on the Performance of WCDMA HSDPA Within Macro Cells. Author: Mathias Nyman Supervisor: Prof. Sven-Gustav Häggman Instructor: Kimmo Hiltunen, Lic.Sc.(Tech.). Contents. 1. Background, Research Objectives and Methods. 2. Basics of HSDPA.

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The Impact of Indoor Traffic on the Performance of WCDMA HSDPA Within Macro Cells

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  1. The Impact of Indoor Traffic on the Performance of WCDMA HSDPA Within Macro Cells Author: Mathias Nyman Supervisor: Prof. Sven-Gustav Häggman Instructor: Kimmo Hiltunen, Lic.Sc.(Tech.)

  2. Contents 1. Background, Research Objectives and Methods 2. Basics of HSDPA 3. Simulated Environment and HSDPA Parameters 4. Simulations and Results 5. Conclusions

  3. Background and Objectives • HSDPA starting to appear in 3G networks • Coverage is a crucial factor for success – macro cell coverage in the first place • Fraction of indoor packet data users is estimated to be 70% in the future  building penetration loss • The aim of this thesis is to study how the network performance is affected by the indoor traffic • Research methods: Litterature study (HSDPA and propagation models) and computer simulations

  4. Contents 1. Background, Research Objectives and Methods 2. Basics of HSDPA 3. Simulated Environment and HSDPA Parameters 4. Simulations and Results 5. Conclusions

  5. Shared Channel Transmission • New HS-DSCH Transport Channel • Dynamically shared power and code resource SF=1 SF=2 Channelization codes allocatedfor HS-DSCH transmission 8 codes (example) SF=4 SF=8 SF=16 Basics of HSDPA TTI Shared channelization codes

  6. Shared Channel Transmission • New HS-DSCH Transport Channel • Dynamically shared power and code resource HS-DSCH Total available cell power Dedicated channels (power controlled) Common channels (not power controlled) Basics of HSDPA

  7. Shared Channel Transmission • New HS-DSCH Transport Channel • Dynamically shared code resource • Adaptive Modulation and Coding • Data rate adapted to radio conditions • 2 ms time basis Basics of HSDPA

  8. Shared Channel Transmission • New HS-DSCH Transport Channel • Dynamically shared code resource • Fast Scheduler • 2 ms time basis • Round Robin, Proportional Fair or Max-C/I • Adaptive Modulation and Coding • Data rate adapted to radio conditions • 2 ms time basis • Hybrid ARQ • Soft combination of multiple attempts Basics of HSDPA

  9. Contents 1. Background, Research Objectives and Methods 2. Basics of HSDPA 3. Simulated Environment and HSDPA Parameters 4. Simulations and Results 5. Conclusions

  10. Simulated Environment • Seven 3-sector sites, wrap-around • Both outdoor and indoor users • COST-WI propagation model • Shadow fading std: 10 dB • Multipath channel: 3GPP Typical Urban • Position dependent building penetration loss • Only HSDPA traffic

  11. HSDPA Parameters • Modulation: QPSK / 16QAM • HS-PDSCH codes: 10 • Scheduling Policy: Proportional Fair • GRAKE Receiver • Traffic type: Interactive, 200kB data packets

  12. Contents 1. Background, Research Objectives and Methods 2. Basics of HSDPA 3. Simulated Environment and HSDPA Parameters 4. Simulations and Results 5. Conclusions

  13. HS-DSCH Total available cell power Dedicated channels (power controlled) Common channels (not power controlled) Impact of Indoor Users • Building penetration causes the A-DCH power to be increased • HS-power is also attenuatedlower CIR • Increased transmission delay

  14. Power distribution (non-HS channels) • Very little power reserved for the non-HS channels when most of the users are located outdoors • As the fraction of indoor users increase, more power is used by the non-HS channels.

  15. Active A-DCHs per cell • As the fraction of indoor users increase, there will be more simultaneous active links per cell • Note that the number of available A-DCHs is 84 in these simulations

  16. Network performance for different fractions of indoor users • The network performance is clearly decreasing as the fraction of indoor users increase.

  17. Floor height gain • The performance is worse for the ground floor users (dashed lines) due to the floor height gain. • Ground floor users are exposed to ~14.5 dB more path loss than the top floor (6th floor) users.

  18. Indoor margin • The system performance is presented for different path loss values when all users are located outdoors • An additional path loss of 19 dB corresponds to the performance of the case with an indoor user fraction of 75%. • Appropriate ”indoor margins” can be taken into account if the amount of indoor users can be estimated.

  19. Contents 1. Background, Research Objectives and Methods 2. Basics of HSDPA 3. Simulated Environment and HSDPA Parameters 4. Simulations and Results 5. Conclusions

  20. Conclusions • Larger fraction of indoor users  decreased network performance • Estimation of the indoor usage will help when designing the network (indoor margin). • A cost-effective macro cellular solution will be suitable in the initial phase, dedicated indoor systems etc. will be required later • Further study: Real network measurements including other traffic than HSDPA, follow-up on HSDPA usage (share of total traffic, amount of indoor usage, etc.)

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