Let’s Get Real! Non-Line-of-Sight Wireless Backhaul for LTE Picocell Deployments


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Let’s Get Real! Non-Line-of-Sight Wireless Backhaul for LTE Picocell Deployments

  1. 1. Cambridge WirelessSmall Cell SIG31st January 2013Let’s Get Real!Non-Line-of-Sight Wireless Backhaulfor LTE Picocell DeploymentsPeter ClaydonManaging Director, Airspan UKv1
  2. 2. A definition of Small Cells…• There are many different definitions • This is ours (for the purpose of this presentation) 1 • Comprehensive Suite of Flexible Back Uses “official” Small Cell Forum use case names• Three types of small cells Flexible Assembly Copper 1. Home and Enterprise • + Indoor, Low Power (typically 100mW) ADSL/VDSL • “Traditional” femtocellsRadio Transport 2 2. Metro FE / POE • Outdoor, open access • Higher power (1W) Cable • Focus of this presentation 3. Rural - Micro and Compact Macro Cells 3 MicroWave • All-in-One outdoor base stations • Much higher power (2-10W), open access • Optimized for non-traditional Small Cell locations (Rooftops, Sides of Buildings etc…) Optical MW / TDD FE / POE ADSL / VDS In case of no wire line backhaul 2
  3. 3. Small Cell HetNets = Network Capacity Enhancement• Small Cells will deliver huge network capacity increases… F Macro-only F 1 HetNet LTE F LTE Network 1 F 1 Network F 1 F1 1 F1 F F 1 F F F 1 F 1 F 1 1 F 1 F 1 F F1 F 1 1 F 1 1 F1 F 1 1 F F F F 1 F 1 F 1 1 1 1 F1 F F1 F 1 F F 1 F F 1 1 F 1 F 1 F F 1 F 1 F 1 F1 1 F 1 1 F 1 F1 1 F 1 F F 1 F 1 F 1 F 1 1 Capacity Enhancement comes from Aggressive Frequency Re-use 3
  4. 4. The Power of LTE-Advanced: eICIC and SON• Enables aggressive deployment Dynamic Resource Block of LTE small cells Allocation All Resource Blocks • Allowing Time and Frequency resource block re-use. Frequency• Closely Coupled (Macros) All Resource Blocks • Typically a Tri-Sectored Base All Time Resource Station – sectors share the same Blocks frequency. X2 communication over Ethernet or internal messages between sector RRMs Closely Coupled: Sectors at same cell location• Loosely Coupled (Small Cells) Dynamic Loosely Coupled: Omni • Auto-Optimizing and Configuring Resource Block Cells at different locations cells that share the same spectrum Allocation (i.e. N=1 re-use). X2 communications over wide-area backhaul to other cells 4
  5. 5. Small Cells and Frequency Re-use: eICIC at WorkMacro Cell Macro Cell Pico Cells• Small cell capacity gains come from better frequency re-use. • LTE-Advanced protocols map UEs to the optimal cell (Macro or Pico), i.e. with the best signal conditions (better MCS and MIMO). Mapping is independent of RSSI (with Cell Range Extension). • Small cells are typically “Buried in the clutter”, so that propagation is contained and extensive re- use of frequencies can happen. • LTE-Advanced eICIC and Almost Blank Sub-frames (ABS) features ensures potential areas of interference between Macro-Pico, and Pico to Pico are “mapped out”. Small Cells are deployed in locations that are generally Non-Line-of-Sight from Macro Cells, or other Pico Cells to maximize capacity gains 5
  6. 6. Small Cell Networks: Capacity Enhancement 20x Macro 18x Cell Edge 16x Median SON 14x 12x Assumptions*: 10x N=1 reuse 10 MHz FDD 8x 4 Pico cells per Macro cell 6x eICIC, SON, High Power 4x Macro, Hotspot Deployment 2x 0x Downlink Uplink • LTE-Advanced eICIC and SON technology can deliver large capacity gains with even limited numbers of Pico cells • Macro cell footprint DL traffic boosted from 33Mbit/s to >130Mbit/s (with 4 Picos) – in Busy Hour • Actual gains vary significantly depending on number of Pico cells deployed per Macro cell, location of Pico cells, Busy Hour, versus Non-Busy Hour traffic patterns. 4x Gains using 4 Pico Cell per Macro Cell in Same Spectrum Allocation* 3GPP TS 36.814, Macro ISD 1500m, Full Buffer Model, Even UE Distribution, Cell Range Extension (12dB), 10 MHz (FDD) at 2.6 GHz 6
  7. 7. Small Cell Backhaul Requirements 200 180 Busy Hour Non Busy Hour 160 Average per Pico 140 Peak per Pico (90%) Mbit/s 120 100 80 60 40 20 0 Macro Only 1 Pico 2 Pico 3 Pico 4 Pico • Assumptions: LTE-A eICIC, Hot Spots Deployment, Urban Model • Busy Hour vs. Non Busy Hour with statistical sharing of backhaul • Typical Backhaul for LTE Small Cells is around 40 Mbit/s (for 10 MHz FDD) • Non Busy Hour Pico backhaul traffic typically ~1.3 times Busy Hour • Backhaul needed per Pico decreases as number of Pico increases* 3GPP TS 36.814, Macro ISD 1500m, Full Buffer Model, Even UE Distribution, Cell Range Extension (12dB), 10 MHz (FDD) at 2.6 GHz 7
  8. 8. Summary• eICIC, and SON are key features for building LTE Small Cell networks • These allow aggressive frequency re-use when cells are optimally located• Small cells will generally be located in NLOS locations • They can’t see Macro Cells, and mostly can’t see other Pico cells (by design)• Small cells typically require ~40 Mbit/s backhaul per node • If backhaul is less than 40 Mbit/s overall network capacity gains reduce These technical characteristics drive the backhaul requirements for Small Cells 8
  9. 9. Let’s Get Real! Outdoor Picocell Deployments Side of Building Metal Scaffold Rooftops Wooden Street Lamps Low-rise cell Poles Telephone Pole Towers A variety of deployment locations 9
  10. 10. Let’s Get Real! LTE Small Cell Deployment 10
  11. 11. Let’s Get Real! LTE Small Cell Deployment Containing LTE Small Cell Propagation maximizes capacity gains 11
  12. 12. Small Cell Backhaul Traffic• Three types of traffic from a small cell • Signaling and Management Traffic, S1 and X2 interfaces – Highest Priority, Latency Sensitive, Mission Critical • Synchronization Messages, 1588v2, Sync-E (assisting GPS), often critical • Real-Time Services Traffic, Voice and Video, Cloud UI, Real-time Gaming etc… • Non Real-Time Services Traffic, variety of types• All LTE Traffic is classified using QCIs • Each UE contains multiple traffic flows with different requirements • VoLTE requires Real-Time, Low Latency support 12
  13. 13. Impact on QoS of contended backhaul…• If backhaul is contented (in any way), the QoS Real-Time and GBR Non Real-Time and Non-GBR Services and service reliability delivered over the LTE Uu Sync, Mgmt S1 and X2, Services interface becomes impaired. • If the backhaul randomly introduces latency and/or reduces the capacity allocated to service flows (especially GBR), the service is negatively impacted.• Therefore, any backhaul solution must ensure eNodeB Instantaneous Offered Load that the LTE radio-interface QoS is respected Traffic and maintained across the contented backhaul. • Typically this requires a detailed understanding of the LTE Air-Interface • Not something that can easily be done using code-point Backhaul markings, or other simple packet marking (ToS bits) Instantaneous • Any contention based scheduling must take LTE Air- Backhaul Interface QoS needs into account. Capacity • Ensuring Signaling gets and Real-Time / GBR service gets served first LTE QoS must be supported by any contented backhaul solution for LTE Small Cells 13
  14. 14. Wireless Backhaul Characteristics• The capacity of “Ethernet based” wireless backhaul varies; • Wireless has variable capacity by design • Applies to both LOS and NLOS wireless solutions • LOS capacity varies due to rain-fade • P-MP backhaul shares it’s capacity over multiple nodes • Takes advantage of statistical multiplexing • Best when dimensioned using average, or mean traffic, not peak traffic• Two Choices • “Over provision” wireless backhaul to every small cell • Ensure backhaul capacity always exceeds offered load. Economics are unattractive! • LOS P-P links $,$$$’s per small cell (typically twice the cost of the small cell) • Dimensioning using “average demand” using P-MP • Makes economics attractive • Implies support for QoS mechanisms in backhaul radio interface LTE small cell deployments must solve the QoS problem to be successful. 14
  15. 15. Solution: Outdoor Picocell deployment with Fibre eICICDynamicResource BlockAllocation NLOS NLOS NLOS NLOS 30Mbit/s  60Mbit/s  60Mbit/s  30Mbit/s   10Mbit/s  20Mbit/s 150Mbit/s   20Mbit/s  10Mbit/s  50Mbit/s Uncontende d 200 Mbit/s Metro Ethernet Fibre • Typical deployment of 5 LTE Pico cells sharing a single Fibre connection • Metro Ethernet service economically serves 5 LTE Pico Cells. Business case works… 15
  16. 16. Solution: Picocells with P-P LOS and P-MP NLOS Macro Cell eICICDynamicResource BlockAllocation NLOS NLOS NLOS NLOS 30Mbit/s  30Mbit/s  60Mbit/s  60Mbit/s   10Mbit/s  20Mbit/s  20Mbit/s  10Mbit/s • Deployment model mirrors the use of Fibre • Backhaul comes from Macro cells sites • Uses LOS P-P to a small cell with LOS to Macro cell 16
  17. 17. P-MP NLOS Backhaul: Cooperative QoS  Real-Time LTE QCI Service Flow Data LTE Pico Access Coverage NLOS Wireless Backhaul LTE Pico Coverage Access LTE QCI Coverage Scheduler Information LTE Pico P-MP NLOS Access Backhaul Base Coverage Fiber Station Node• In Cooperative QoS mode the Backhaul Scheduler maintains visibility of Pico scheduling requirements for UEs (MSs), tracking QoS commitments on bandwidth, latency and priority• In addition the Backhaul Scheduler also has visibility of the backhaul radio interface and it’s interference environment.• The scheduling by the Pico cells takes accounts of both requirements to deliver high performance over the backhaul and end-to-end QoS over the 4G LTE or 4G WiMAX Pico access interface 17
  18. 18. Let’s Get Real! AirSynergy: Airspan’s Small Cell A compact, low power, multi-standard, carrier-class LTE eNodeB with integrated backhaul Self Optimizing “Single Box, Optimised” Access and Backhaul Environment Form-Factor Visuals – Example renderings Initial renderings indicating the potential level of visualisation Environment Visuals – Rural 2 Low-res preview urban setting, visible, eye-level ruralAirspan | AirSynergy Gen2 | Environment visuals – low res previews | 23 Feb 2012 | P.4 Integrated High Capacity Backhaul Airspan | AirSynergy Gen2 | Environment visuals – initial image selection | 22 Feb 2012 | P.6 with Relay Capabilities 18
  19. 19. Let’s Get Real! Carrier Trial - Feeder Base 19
  20. 20. Let’s Get Real! Carrier Trial - Feeder Terminal A 20
  21. 21. Summary and Conclusions• LTE small cells can dramatically increase the capacity of LTE networks• The enabling technology for LTE small cell is cost effective backhaul • Unless the backhaul costs are right, small cell deployment won’t happen.• Outdoor LTE small cells will mainly be deployed in NLOS locations • Requires NLOS Backhaul technology, as Fiber based solution uneconomic• Supporting QoS across any backhaul technology necessary There is a Small Cell Backhaul Solution! Core of the solution is NLOS P-MP Technology with QoS support augmented with Fibre and P-P LOS Wireless Backhaul 21
  22. 22. Let’s Get Real! See it for real Demonstration of eICICCell Range Extension & Almost Blank Subframes The power of Cooperative QoS 22
  23. 23. MWC - Picocells 23
  24. 24. MWC - Picocells with LTE-Advanced 24
  25. 25. Come and see usHall 6 Booth #D90 25