optical transport scenarios for future radio access networks
TRANSCRIPT
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Optical Transport Scenarios For Future Radio Access Networks
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Optical Transport Scenarios | Public | Ericsson AB 2015 | 2015-05-13 | Page 2
Radio scenarios: backhaul, fronthaul, CRAN, CPRI Optical transport scenarios: , SDN, Virtualization 5G, 50B, 1000x, 2020
Outline
Disclaimer: this presentation refers to research topics and its finalized to scientific dissemination in the context of PACE workshop. No product related information is contained in this presentation.
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Optical Transport Scenarios | Public | Ericsson AB 2015 | 2015-05-13 | Page 3
Radio Scenarios Backhaul, Fronthaul, CRAN, CPRI
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RAN Deployment scenarios
Conventional Backhaul BB processing at each cell
BH
Backhaul: the transport network connection between the macro base station, the small cell or the centralized DU pool and the switch site (where the radio controller and/or the core network nodes are located).
Fronthaul: the transport network connection between the remote radio units and the baseband unit. The distance between RRUs and DU pool can be extended up to tens of km, where limitation is coming from processing and propagation delays.
DU RU
BH
DU RU
Local Fronthaul BB processing of small cells is done at macro cell
BH
RRU
RRU
RRU
RRU
RRU
RU
CRAN Centralized BB processing and geographical fronthaul
BH
DU POOL
RRU
RRU RRU
RRU
RRU RRU
RRU RRU
RRU RRU
RRU RRU
RRU
RRU
RRU
RRU
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BH
DU POOL
RRU
RRU RRU
RRU
RRU RRU
RRU RRU
RRU RRU
RRU RRU
RRU
RRU
RRU
RRU
CRAN A Term with many meanings
CRAN is the term used to describe an architecture in which the baseband processing is centralized into one entity that is called DU pool or Baseband Hotel.
The letter C can be interpreted as: cloud, centralized (processing), cooperative radio, clean. No agreed definition. For Ericsson, C stands for Coordinated.
Usage of radio resources is optimized thanks to coordination. Treating digital resources as a single, grouped resource, allows
load sharing and balancing across the DU pool, offering high availability and seamless recovery.
DU resources are no longer dimensioned for peak requirements of each individual site, but for the aggregated requirement of the cell served by the pool, taking advantage of the distribution of the traffic over time and space.
CPRI CPRI
CPRI CPRI
CRAN Centralized BB processing and geographical fronthaul
CPRI Data transmission between RRUs and DU.
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CPRI Common Public Radio Interface
CPRI is the radio interface protocol widely used for IQ data transmission between RRUs and DUs in CRAN scenario. One of the technical challenges for the CRAN architecture is the bandwidth required for CPRI data transmission. Other constraints are latency, symmetry, jitter. These comes from need to transport time synchronization signals.
Transport
Layer 1
Baseband
Layer 2 Control & Clock
SAPCM
SAPIQ
SAPS
Layer 1
Layer 2
SAPCM
SAPIQ
SAPS
Remote RF
Remote Radio Unit DU Pool
Fronthaul
Backhaul
LTE 20 MHz 2x2 MIMO 150 Mbps x sector
CPRI 2.5 Gbps
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OPTICAL TRANSPORT Scenarios For the different RAN Architectures
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Optical Transport Scenarios
Access Metro/Aggr. Core
Backhaul Segment
Access Ethernet Clients Up to 1 Gbps rate Up to 20 km Low cost High volumes W/copper areas Convergence
Metro/Aggregation Ethernet Clients 10 Gbps and more Up to 100 km Resiliency mandatory Flexibility and elasticity
Conventional Backhaul
Fronthaul Metro/Aggr. Core
Fronthaul Segment Residual Backhaul
DU POOL RRU
Metro/Aggregation CRAN has an impact on BH because the number of BH nodes is reduces (one or more levels of aggregation are skipped).
Fronthaul CPRI transport Maximum CPRI
rate is 10 Gbps Stringent latency
requirements limit distance
CPRI over optics
RRU
CRAN
RBS
DU RU
DU RU
ETH ETH CPRI ETH
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Indoor Small Cell Indoor coverage Wi-Fi optional Office, restaurant
Outdoor Small Cell Outdoor coverage Roof, pole, lamp-post or wall mounted
Macro Cell Area
Coverage
In 1 Kmq of dense urban area: 29 Macro Cells, 200 m ISD 9 outdoor Small Cells x Macro for maximum gain 20-40% of buildings shall be integrated with indoor solutions with
up to 30% more gain with clever Wi-Fi installation
DU POOL
In 1 Kmq of dense urban area: Each Macro (LTE 20 MHz, 3 sect.): 2.5 Gbps CPRI flow -> 220 Gbps
- 1 ring, 24 @10G Each Outdoor Small (1 sect.): 2.5 Gbps flow -> 650 Gbps additional
- 4 ring, 24 @10G
RRU
RRU
RRU RRU
RRU
RRU
RRU RRU
Fronthaul
Bandwidth Requirements EXAMPLE: Dense Urban Scenario
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SDN EXAMPLE: Cooperative Multipoint (CoMP) Accomplish Downlink Cooperative Multipoint (DL CoMP) from multiple cell sites to a single User Equipment (UE)
CENTRAL OFFICE
UE X2
Fixed topology without hub switch at DU pool
DU1 and DU2, in charge of the respective cell sites, communicate over a logical point-to-point link (e.g. X2) and then transmit the same user data over parallel optical fronthaul links. The data is then delivered to the UE.
DL CoMP is performed using the computational resources of both DU1 and DU2.
Topology path
DU1
DU2 SD
N C
ontr
olle
d O
ptic
al S
witc
h
UE
Re-configurable topology and SDN controlled hub switch at DU pool
A new path can be created from DU1 to the second cell site through SDN-controlled optical/electrical switching, such that DL CoMP is performed using just the computational resources of DU1 releasing DU2.
Moreover, DU1 and DU2 can be interconnected directly through the SDN controlled switch, with inter-DU connectivity managed centrally by the SDN controller, reducing latency compared to distributed control and offloading the inter-DU interface.
CENTRAL OFFICE
SDN ORCHESTRATOR
DU1
DU2
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Virtualization of various network functions, including the optical network, will enable the realization of a multitude of functionalities in a virtualized data centre environment, eliminating the need for specialized hardware.
Orchestrator
Radio Spectrum
Availability
Optical Transport Network
Virtualization
Virtual
Digital Unit
Optical Transport Network Virtualization Systems
(servers)
Remote Radio Units
Virtual Resources
Physical Resources
Radio Resource Management
RRU VDU
Virtualization EXAMPLE: Virtual Digital Unit
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5G meeting the expectations of the Networked Society
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5G
2000 2010 2020 1990 2015
3G
4G
New wireless technologies
Wi-Fi
5G
GSM 5G =
evolution of existing standards
+ complementary
new technologies
Wide range of use cases Wide range of requirements
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First 5G mobile Phone
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5G Key Points
Massive growth in Connected Devices
Massive amount of communicating machines
50 billion connected devices
Massive growth in Traffic Volume
Further expansion of mobile broadband Additional users and increased usage
Additional traffic due to communicating machines
>1000x
Wide range of Requirements & Characteristics
Multi-Gbps in specific scenarios
Hundreds of Mbps generally available
Ultra-low latency
New requirements and characteristics due to communicating machines
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Optical solutions for 5G will need to:
be programmable to support increasingly diverse service requirements for the wide range of applications envisioned in 5G
support higher capacities and an increasing number of cell sites
facilitate radio interference coordination between sites, by connecting RRUs with DUs with severe latency constraints
address cost and energy constraints by exploiting emerging optical components/devices enabled by integrated photonics
facilitate resource sharing among different network actors
be ready for the unexpected
Optical Transport Challenges
ITU Peak data rate User data rate Mobility Latency Traffic volume density Connection density Energy efficiency
METIS (EU Project) Experienced end user throughput Latency Energy efficiency Traffic volume density
NGNM Consistent user experience Device power consumption Coverage Resource efficiency Connectivity transparency Context awareness
Reliability, availability Security Mobility Cost efficiency Ease of deployment Operation efficiency
Wide Range of Requirements
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Slide Number 1OutlineRadio ScenariosBackhaul, Fronthaul, CRAN, CPRIRANDeployment scenariosCRANA Term with many meaningsCPRICommon Public Radio InterfaceOPTICAL TRANSPORT ScenariosFor the different RAN ArchitecturesOptical Transport ScenariosBandwidth RequirementsEXAMPLE: Dense Urban ScenarioSDNEXAMPLE: Cooperative Multipoint (CoMP)VirtualizationEXAMPLE: Virtual Digital Unit5Gmeeting the expectations of the Networked SocietySlide Number 13First 5G mobile Phone5G Key PointsOptical Transport ChallengesSlide Number 17