1. Cloud RAN for Mobile Networks
A Technology Overview

2. Agenda
• Overview
• What is C-RAN?
• Traditional Mobile Network
• Architecture Of C-RAN
• Advantages and Challenges of C-RAN
• Future Scope and Conclusion

3. Overview

4. Overview
• Mobile Transmission volume is forecasted to
grow by 13 folds from 2012-2017.
• Add complex structure of Heterogeneous and
Small cell Networks.
• Multiple Input Multiple Output (MIMO) .
• inter-cell interference levels and high costs .

5. Overview
• Total Cost of Ownership
• CAPital EXpenditure (CAPEX) and OPerating
EXpenditure (OPEX)

6. Cloud RAN
Mobile Backhaul
Network

7. Cloud RAN
• Adapt to non- uniform traffic and utilizes the
resources.
• Can be added and upgraded easily.
• Virtualized BBU Pool can be shared by different
network operators as a cloud service.
• Increase spectral efficiency and throughput.
• Delay during intra- BBU Pool handover reduced.

8. Cloud RAN
Centralization
• Improving performance.
• OPEX reduction 30%-
50%.
• Antenna is needed at the
cell site.
• Cheaper to centralize
RAN.
Virtualization
• Network function
virtualization (NFV).
• Reduce processing
requirements by as much
as 75%.
• Switch between base
station vendors.

9. Cloud RAN
• Fronthaul-between the baseband units and the remote
radios.
• A single 20 LTE channel requires about 2.5 Gbps.
• Fiber network-cost breaks the business.
• Virtualization of the physical layer (PHY).
• General purpose processors are less efficient

10. Cloud RAN
• Small cells, part of HetSNets and Massive MIMO.
• Difficult to upgrade and repair.
• Energy efficiency of large scale Small Cell Networks is
higher compared with Massive MIMO.
• Total transport cost per Mb/s is highest for macro cell-
2200$, medium for C-RAN—1800$ and 3 times smaller
for small cell—600$.

11. Cloud RAN
• Fundamental aspects of C-RAN architecture.
• Advantages of this architecture.
• Challenges of this architecture.
• State- of-the-art hardware solutions.
• Virtualization techniques.
• Possible deployment scenarios.
• Summarize ongoing work.

12. Architecture of C-RAN

13. Traditional Mobile network
• The area in which mobile networks covers is divided into
cells.
• Hence mobile networks are called as cellular networks.
• In a cellular network, communication with a base station.
• Base station: Baseband processing module and Radio
module.
• Baseband processing ( coding, modulation, sampling ,
quantization) ; radio module (digital processing, filtering,
power amplification)

14. Traditional Architecture
• The baseband processing and radio integrated in a base
station.
• Antenna few meters away.
• X2 interface defined between
base stations
• S1 interface connects base station
to the mobile core network.
• Traditional architecture for 1G and 2G deployment
• Figure for traditional macro base station

15. • The base station separated into Remote radio head(RRH)
and base band signal processing part (BBU)
• RRH : interface to the fiber and performs
D/A & A/D conversions, power amplification,
digital processing etc.
• BBU called as DU(Data unit): A unit
that processes baseband in
telecomm systems.
• It is placed in the equipment room
and connected with RRH via
optical fiber
• Basic Structure for 3G
Base Band with RRH

16. • The distance between BBU and RRH can be extended up
to 40 km( limitation is processing and propagation delay)
• Need to keep the BBU equipment in a more convenient,
easily accessible, enabling cost savings on rental and
maintenance.
• One BBU can serve many RRHs
• RRHs connected in a daisy chained structure.
• To optimize BBU utilization, BBUs are centralized into
one entity BBU pool.
Base Band with RRH

17. C-RAN Architecture
• A virtual BBU pool connected to various RRHs.
• BBU pool consists of general purpose processors to perform
baseband processing .
• C-RAN mobile LTE network.

18. • The front haul part spans from the RRHs sites to the BBU
pool.
• The backhaul connects to the BBU pool with the mobile
core network .
• RRHs are co-located with antennas, connected to the
high performance processors in the BBU pool.
C-RAN Architecture

19. Comparison between Base stations
Architecture Radio and Baseband
functionalities
Problems it
addresses
Problems it causes
Traditional
base station
Co-located in one unit ---- High power
consumption &
resource
underutilization
Base station
with RRH
Spitted between RRH and
BBU. BBU 20-40 kms away.
Low power
consumption
Resources are
underutilized
C-RAN Spitted between RRH and
BBU. BBUs from many sites
co-located into a pool, 20-40
kms away.
Even lower
power
consumption.
Cost reduction
Proper utilization of
resources.

20. Advantages and Challenges of C-RAN

21. Advantages of C-RAN
Basically divided into 4 categories of advantages:
• Adaptability to Non Uniform Traffic and Scalability
• Energy and cost savings
• Increase of Throughput, decrease of delays
• Ease in network upgrades.

22. Advantages of C-RAN
Adaptability to Non Uniform Traffic and Scalability
• Peak traffic load 10 times higher than the off-the-peak
hours.
• The overall utilization rate can be improved in C-RAN.
• Number of BBUs reduced by 75% in Tokyo
Metropolitan Area.
• Statistical multiplexing gain varies between 1.2 and 1.6
thereby saving 17%–38% .
• Aggregation of 57 sectors in a single BBU Pool saves
more than 25% of the compute resources.
• Load balancing features enabled on both the BBU side
and the cells side.

23. Advantages of C-RAN
Energy and Cost Savings
• Total of 41% of OP-EX spent on electricity of a cell
site.
• Reduced as number of BBUs in a C-RAN is reduced.
• 46% spent of OPEX spent on cooling Resources.
• RRHs cooled by natural air in C-RAN.
• All in all 67%-80% power consumption reduced using
C-RAN.

24. Advantages of C-RAN
Ease in Network Upgrades and Maintenance.
• C-Ran architecture with several Co-Located BBUs eases
network maintenance.
• BBU pool automatic reconfiguration absorbs C-RAN
capacity peaks and failures.
• Enables frequent CPU Updates
Decrease of Delays
• The time needed to perform handovers is reduced as it
can be done inside the BBU pool instead of eNBs.
• Hence reducing the delays.

25. Advantages of C-RAN
Increase of Throughput
• Reducing interference achieves greater throughput -
important for LTE and LTE-A.
• Two approaches for addressing for the interference
issue.
– Minimizing Inter-Cell Interference:
– Utilizing Interference Paths Constructively:
• Processing by one BBU pool enables tighter interaction
between base stations.
• 30-50% throughput gain in case of no interference
• Can reach 150% when the interference is present.
• Hence interference for us is good.

26. Advantages of C-RAN
Increase of Throughput

27. Advantages of C-RAN(Summary)
• A centralized BBU Pool enables an efficient utilization
of BBUs and reduces the cost of base stations
deployment and operation.
• Reduces power consumption.
• Provides increased flexibility in network upgrades.
• Adaptability to non-uniform traffic
• More attractive SLAs can be provided by the
operators.

28. Challenges
Before the commercial deployment of C-RAN architectures a
number of challenges need to be addressed:
• Need for High Bandwidth (high overhead on the optical
link between RRH and BBU Pool)
• Transport network needs to be cost efficient, support
strict latency and jitter requirements.
• BBU Cooperation, Interconnection and Clustering.
– Cooperation between base stations is needed to
support CoMP in terms of sharing the user data,
scheduling at the base station and handling channel
feedback information to deal with interference.

29. Challenges
– Co-location of many BBUs requires special security
and resilience mechanisms.
– C-RAN must provide a reliability that is better or
comparable to traditional optical networks like SDH.
Mechanisms like fiber ring network protection can be
used.
• Virtualization Technique:
– Needs to be proposed to distribute or group
processing between virtual base station entities and
sharing of resources among multiple operators.

30. CLOUD RAN FUTURE
• Joint Effort
• Prototype
• Conclusion

31. PRIMARY FOCUS
• Evaluation for Cloud Computing
• Architecture
• Integration
So what inference can we take out of these
focusses ?

32. PRIMARY FOCUS
• Evaluation for Cloud Computing
• Architecture
• Integration
• So what inference can we take out of these focusses ?
To maximize Efficiency with minimum costs on
architecture.

33. Challenges and Research Direction
• Quantifying multiplexing gains, energy and cost savings
• Combining an increase throughput.
• Wireless front haul for C-RAN
• Optical front haul for CRAN
• IQ compression
• Moving towards software virtualization solutions
• Deployment Scenarios

34. C-RAN PROTOTYPE
• China Mobile with its industrial partners and Universities
have developed a GPP based CRAN prototype.
• It supports GSM, TD-SCDMA and TD-LTE
• The prototype runs on Intel Based servers and their
respective data centers.
• The Commercial IT Servers processes the sample IQ in
real time.
• PCI-Express, a high-speed serial computer expansion bus
is connected to CPR/Ir interfaces converter, which carries
the signal towards RRH’s.

35. DEPLOYMENT
• China Mobile Field Trial
• Since 2010, China mobile has been conducting trials in various cities.
• Advantages such as cost saving, flexibility and energy saving was
achieved.
• Statistically CAPEX and OPEX were reduced by 53% and 30%
• Korea Telecom announced at the end of 2011 their plans on the first
commercial deployment.
• They developed so called Cloud Computing Center(CCC)
architecture together with Samsung who provides modems and Intel
who provides servers and data centers.
• One thousand servers based on GPP are planned to be used in one
BBU pool where architecture manages 144 base stations per server.

36. CONCLUSION
• The presentation presents a detailed overview of a novel
mobile architecture called C-RAN and discusses the
advantages and challenges that need to be solved
before its benefits.
• C-RAN has the potential to reduce networks deployment
and operation cost and at the same time, improve
system, mobility and coverage performance as well as
energy efficiency.
• The concept is more under research and has been
supported world wide by corporate houses.

37. QUESTIONS ? ? ?

38. THANK
YOU