Cloud RAN for Mobile Networks A Technology Overview

Agenda

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

Overview

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

.

Overview

• Total Cost of Ownership • CAPital EXpenditure (CAPEX) and

OPerating EXpenditure (OPEX)

Cloud RAN

Mobile Backhaul Network

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.

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.

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

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$.

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.

Architecture of C-RAN

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)

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

• 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

• 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

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.

• 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

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.

Advantages and Challenges of C-RAN

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.

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.

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.

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 UpdatesDecrease 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.

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.

Advantages of C-RAN

Increase of Throughput

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.

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.

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.

CLOUD RAN FUTURE

• Joint Effort• Prototype• Conclusion

PRIMARY FOCUS

• Evaluation for Cloud Computing• Architecture• Integration

So what inference can we take out of these focusses ?

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.

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

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.

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.

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.

QUESTIONS ? ? ?

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