• 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 .
7. Cloud RAN
• Adapt to non- uniform traffic and utilizes the
• 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
• Improving performance.
• OPEX reduction 30%-
• Antenna is needed at the
• Cheaper to centralize
• Network function
• Reduce processing
requirements by as much
• Switch between base
9. Cloud RAN
• Fronthaul-between the baseband units and the remote
• 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.
13. Traditional Mobile network
• The area in which mobile networks covers is divided into
• Hence mobile networks are called as cellular networks.
• In a cellular network, communication with a base station.
• Base station: Baseband processing module and Radio
• Baseband processing ( coding, modulation, sampling ,
quantization) ; radio module (digital processing, filtering,
14. Traditional Architecture
• The baseband processing and radio integrated in a base
• Antenna few meters away.
• X2 interface defined between
• 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
• It is placed in the equipment room
and connected with RRH via
• 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
• 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
• 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.
19. Comparison between Base stations
Architecture Radio and Baseband
Problems it causes
Co-located in one unit ---- High power
Spitted between RRH and
BBU. BBU 20-40 kms away.
C-RAN Spitted between RRH and
BBU. BBUs from many sites
co-located into a pool, 20-40
Proper utilization of
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
• The overall utilization rate can be improved in C-RAN.
• Number of BBUs reduced by 75% in Tokyo
• 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
• 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
24. Advantages of C-RAN
Ease in Network Upgrades and Maintenance.
• C-Ran architecture with several Co-Located BBUs eases
• 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
– 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.
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
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.
– 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
• Virtualization Technique:
– Needs to be proposed to distribute or group
processing between virtual base station entities and
sharing of resources among multiple operators.
32. PRIMARY FOCUS
• Evaluation for Cloud Computing
• So what inference can we take out of these focusses ?
To maximize Efficiency with minimum costs on
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
• PCI-Express, a high-speed serial computer expansion bus
is connected to CPR/Ir interfaces converter, which carries
the signal towards RRH’s.
• 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
• Statistically CAPEX and OPEX were reduced by 53% and 30%
• Korea Telecom announced at the end of 2011 their plans on the first
• 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.
• 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
• The concept is more under research and has been
supported world wide by corporate houses.