1. Understanding Small-Cell Wireless Backhaul
Thursday, December,   Dr Abdellah Chehri

2. Agenda Introduction Physical Layer Parameters Interference Management
Small-Cell Drivers
Deployment Scenarios
Physical Layer Parameters
Link Budget (X1000 HUB/RBM)
Interference Management
Benefits of a Dual-carrier, Licensed/Unlicensed NLOS Backhaul approach
Network Management Components
Current Hot Topics 2

3. Introduction: Putting the Challenge in Perspective
Smartphones & Social Networking Changed Everything
Deployment Implications
Coverage
Capacity
Voice-centric network
5 Macro BTS/sq. km
Data-centric network
20 Compact BTS/sq. km
Backhaul
Mobile data traffic will ~double every year:
2016 is 18x 2011
Small cell base stations (HetNet) provide double the capacity of macro-cells
Hot spot
Not spot
The evolution of the mobile operator’s services, networking technologies, processes and skillsets to a common infrastructure based on the Internet Protocol (IP).
A means to improve mobile operators’ profitability by:
Reducing total cost of ownership
Enabling innovative new services and applications
Accelerating time to market
 4.1 trillion megabits of mobile data was consumed in 2014 
Traditional Backhaul Solutions Do Not Scale in Small Cell Deployments
LOS m-wave does not work; Fiber not economically scalable
Cost Effective, High-Capacity & Reliable Backhaul Technology is Needed for Next Generation Data Networks
* Hans Vestberg, Ericsson President and CEO, 3/23/10 3

4. Introduction: Small-Cell Drivers
To meet 4G capacity needs, higher base station densities are required
The only way to achieve this economically is to deploy small and inexpensive cells around the macro-cell 4

5. Small Cell Backhaul Options
Fiber
Likely to address < 30% of small cell locations
Copper
Not enough copper pairs available to most locations
Radio: Best when looking at both the OPEX and CAPEX.
Wireless <6 GHz (NLOS)
Unlicensed (2.4/5.8 GHz) subject to interference
Licensed – scarce and expensive resource (access)
Microwave frequency band (6 – 38 GHz)
Licensing and equipment cost
Regulated min antenna size
Limited capacity….what about millimeter wave? 5

6. Introduction: Cost & Performance of Small Cell Wireless Backhaul Solutions
High Equipment Cost:
Limited silicon integration
Expensive component cost
High Planning & Deployment Cost
High Maintenance Cost
Capacity
E-band
$18k+
LOS Microwave
$10k+
Cost Threshold
Poor ROI
Low Equipment Cost:
High silicon integration
Larger ecosystem and high economies of scale
Low silicon technology cost
Licensed NLOS
$5k
Reliability Threshold
High order modulation (64QAM)
Very sensitive to transmission impairments
Phase noise
I/Q imbalance
Challenging requirements for SiGe based analogue components
Compensation techniques must be applied in a mixed-signal approach
self-healing algorithms required
Poor Reliability
Unlicensed NLOS
$2k
Lowest Capex /Opex & Reliability
low to no throughput, very high latency & jitter; No QoS
Cost
E-Band (71-76 GHz and GHz)
List price per link

7. Introduction: Mobile backhaul
Mobile backhaul connection by Radio will be more than 50% in 2016.
Source: Infonetics Research (September 2012) 7

8. Spectrum for Backhaul 6 - 38 GHz (licensed) 60 GHz unlicensed (free)
Per link license typically $2K fee
Optimized for speeds up to 350Mbps per channel
60 GHz unlicensed (free)
Excellent for short distances
Gigabit speeds and urban environment friendly
70/80 GHz (lightly licensed)
Per link license <$100
Optimized for Gigabit speeds. 8

9. Spectrum for Backhaul Traditional Microwave Millimetre – E-Band
60 GHz - Unlicensed

10. Introduction: Small-cell backhaul decision tree
Source: Senza Fili 10

11. Sub 6GHz Backhaul requirements
High capacity & spectral efficiency supporting multiple HSPA & LTE compact BTS on one Hub Module
Capacity
High NLOS link availability simplifies design, planning & deployment ( %< 5min/yr)
Low latency <5ms one-way delay
Low jitter <1ms
Reliability
Ease of planning and deployment
Small form factor, easy to deploy wherever needed
Usability
Optimized Product Features Enable Cost Effective Backhaul of
Below Roofline Compact Base Stations 11

12. MBH Deployment Scenario
Deployments required in diverse locations
Large number of nodes required due to coverage needs
Environment & Aesthetics
High capacity – up to 1 Gbps
Low cost (CAPEX & OPEX)
Short deployment lead time

13. Temporary Backhaul Applications
COWs (Cell on Wheels)
Instant coverage at special events
Fast Disaster Recovery
Immediate continuity of service
Temporary Backhaul to New Locations
Rapid new cell deployment
High capacity requirements:
Voice & data services
Traffic peaks
Must be easy to install
Low OPEX
Compact, light-weight, easy to transport
License exempt – immediate deployment, no bureaucratic procedures
Flexible – multi-band radio for on-site band optimization 13

14. Carrier Deployment: Mobile Backhaul
Deploy backhaul hub module on macro-cells
Fiber / Microwave available
One hub per sector
Roll out 1-x micro/pico base stations per sector (PTP/PMP)
Public infrastructure asset (e.g. pole)
RBM height: 6 – 10 m
Link distance < 350 m
R = 350 m
(ISD = 700 m)
< 140 m*
Urban Cell Site Density & Size
3.2
Sites/Sq. km
347
Cell Radius
694
Inter-Site Distance
* Based on 20 micro cells per square km 14

15. Small Cell Backhaul Deployment Challenge
Fiber PoP
Small Cell
Making Backhaul Available Where Small Cells are Required is a Major Challenge.
How to Connect the Small Cells to the Fiber PoP?

16. Solving the Backhaul Challenge: NLOS Backhaul
Source: Siradel
LOS Microwave:
Rely of direct shot to Fiber PoP
Use mesh techniques (costly; long planning, site acquisition cycle)
NLOS Backhaul:
Deploy small cells
Typically only 1 in 7 Small Cells Have Direct Line-of-Sight to Fiber Point-of-Presence.

17. Blinq Wireless Confidential
Link Budget
BLiNQ small-cell backhaul system. Source: BLiNQ
Blinq Wireless Confidential

18. Why Interference Management Makes Sense?
256QAM 6/8
64 QAM 1/2
SUI Category B
30m Hub Module
6m RBM
Typical Deployment
Shadowing results in a large distribution of possible path loss values
For anticipated link budget performance, large majority of sites are adequate for typical spans
Monte-Carlo Simulation: 2.6 GHz
The link budget is not the challenge for NLOS backhaul: focus must be on interference management

19. Why Interference Management Makes Sense?
A dense NLOS backhaul network will be interference limited
Maintaining a good CINR is essential to meet aggregate and peak data rates
Need CINR > 25 dB for 256 QAM
When directional antennas are used, interference level is strongly related to
Angle of Arrival
Shadowing
Distance is not a strong indicator of interference contribution
CINR (dB)

20. A Few Nodes Contribute Most of the Interference Power
6 nodes contribute 97% of interference power
Remaining nodes contribute low levels of interference
CIR (interference power) can be improved by > 15 dB by moving 6 nodes to other resource blocks
6% of Nodes create 97% of the interference power

21. Interference Management
Adaptive Resource Allocation
Coordinated Scheduling: Time/Space/Frequency
Power control
Link level
Network level. 21

22. Interference Mitigation
Interference mitigation is a tri-dimensional optimization problem – use three variables (dimensions) to achieve an optimum solution:
Time
Schedule interferer systems and interfered system on different time zones and /or lower interferer power in the target zone when interfered receives data
Requires: RF Environment Characterization (RFEC) knowledge & SMART Scheduling & Power Control
Frequency
Schedule interferer and interfered on different frequency channels and /or lower interferer power in the target zone where interfered receives data
Requires: RFEC knowledge & SMART Scheduling & Power Control
Space
Beam-forming (pointing to specific RBM direction) minimize interference
Requires: RFEC knowledge & SMART scheduling & Power Control & beam-forming capabilities

23. Benefits of a Dual-carrier, Licensed/Unlicensed NLOS Backhaul approach
Carrier aggregation brings capacity increase with additional channel in unlicensed band for offload
Up to 500 Mbps peak capacity utilizing only 20 MHz of licensed or lightly-licensed spectrum. High capacity using low cost spectrum.
Dual carriers provides redundancy and resiliency for carrier-grade performance
Licensed carrier as control channel provides reliable pipe in cases of unlicensed band interference or avoidance intervals
A combination licensed/unlicensed product provides mechanism for advanced scheduling
Real-time traffic management ties traffic priority to appropriate radio resource
Dual carrier provides opportunity for interference nulling
Unlicensed
Licensed or Shared AP
RBM
HUB
X-1200 combines reliability from licensed carrier and capacity from unlicensed carrier resulting in true carrier-grade NLOS backhaul.

24. What about line of sight?
Large majority of links in urban areas will not have LOS
NLOS solutions will be required
Millimeter wave superior when LOS is available
NLOS can be mitigated by planning
Daisy-chain, Mesh or Ring topologies 24

25. The aesthetics Challenge
Street-level deployment requires a different approach:
Aesthetic
Small footprint
Avenue Link Lite NLOS small-cell backhaul system in sub-6 GHz frequency bands. Source: DragonWave 25 25

26. Current Hot Topics
Smart antennas, MIMO/massive MIMO, and multiuser detection have a key role to play in MBH design.
Adaptive modulation scheme
Multi-Gbps mobile access, >10 Gbps backhaul
Challenges is how to deal with interference
Inter-cluster power management
Energy efficient for backhaul of the future networks.
Low power consumption per bit transmitted (green communication).
Next lecture: ASE, capacity, CoMP, DAS 26

27. Source: Senza Fili 27

28. Industry trends and market overview
BLiNQ small-cell backhaul system. Source: BLiNQ

29. Industry trends and market overview
Source: Bluwan

30. Industry trends and market overview
Source: CCS

31. Industry trends and market overview
Source: Dragowave

32. Industry trends and market overview
Source: Siklu

33. Industry trends and market overview
Proxim Wireless

34. Thank you

35. Wireless Backhaul Microwave Fiber lines Capacity · Up to several Gbps
· Unlimited
Regulation
· Requires spectrum · Visual impact considerations
· Requires right of ways and infrastructures; renovation construction works after trenching
Distance influence on costs and deployment time
· Cost per link with some incremental cost with the distance · Fast deployment time
· Costs increase per feet/meter · Deployment time increases linearly with distance
Terrain
· Suitable for any terrain · Requires line-of-sight between two link end-points
· Becomes costly when trenching in difficult terrain (mountains, deserts, swamps, rocky plains or jungles) · Accessibility - requires access for vehicles along the trenching path
Reuse options
· Equipment can be disassembled and relocated somewhere else
· Fiber, in most cases, cannot be relocated · Copper ducts may be reused for fiber lines
Climate
· Influenced by climate · Adaptive modulation and a proper link planning reduces climate effects
· Normally, not influenced, except for floods

36. Introduction: Wireless Backhaul

37. Introduction: What is the Mobile Backhaul ?
Backhaul portion of the network comprises the intermediate links between the Core Network , or backbone, and the small subnetworks at the "edge" of the entire hierarchical network. Taking information from point A to point B
Backhaul plays a vital role in mobile networks by acting as the link between Radio Access Network (RAN) equipment (Eg: radio basestation) and the mobile backbone network.
Since the introduction of the new mobile generation with the new data networking capabilities, mobile networks and mobile usage has undergone a tremendous change. Once voice was the dominating service at the mobile networks, but nowadays data traffic volume exceeds voice traffic everywhere, where the service is available
This means that backhaul is able to transport mobile data from the end user to the internet (or similar network), mobile networks and traditional telephone networks.
At the same time, backhaul network operators are being required to significantly reduce operational costs in order to compensate for declining Average Revenue Per User (ARPU) and to compete with a host of new competitors and technologies.
Operators are also required to protect (or sufficiently emulate)
core legacy services such as voice, which still account
for a substantial share of revenue.

38. Wireless Backhaul Market Drivers
The story
Mobile bandwidth is growing exponentially – but revenues are not.
Smart Phone Impact
Smart phones account for 15% of the market share today, but they account for 78% of the data traffic.
Massive growth in connected devices communicating machines,
D2D, Car-to-Car Comm ~ 50 billion devices in 2020.

39. Spectrum for Backhaul Traditional Microwave Millimetre – E-Band
60 GHz - Unlicensed