The document discusses the challenges of evolving LTE network architectures to support LTE-Advanced and heterogeneous networks. It outlines issues like network densification increasing costs, challenges of managing more complex networks with various technologies and interoperability concerns. The document then proposes that software defined networking (SDN) and cloud radio access network (C-RAN) architectures can help address these issues by increasing flexibility, scalability and programmability of the network while reducing costs. The summary concludes that SDN and C-RAN approaches will help mobile networks realize the full potential of LTE.

1. LTE-A Challenges and Evolving LTE
Network Architecture
Mobile and Cloud Infrastructure Convergence
Munish Chhabra - Aricent
November 2013

2. Agenda
LTE-Advanced and HetNets
Challenges
Evolving LTE Network Architectures
Summary
Proprietary & Confidential. ©Aricent Group 2013
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3. LTE A & HetNets
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4. Challenges….

5. Network Densification
 Necessity to achieve desired capacity
First Step: Coverage (Macros)
Next Step: Capacity (HetNets)
 Bring network closer to the user
 More radio links, more antennas, higher spectral efficiency
 LTE Advanced + HetNets -> Take capacity gains to the next level
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6. Network Densification (Contd…)
But, More Base Stations lead to …
 More Capex
• Equipment (baseband, radio, antennas) at each site
• Shelter, Air Conditioning, Battery at each site
• Backhaul – Connectivity with core network (cost vs performance)
 Increased Opex
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More Rental and running cost
More trained staff for network planning and maintenence
More site visits for preventive and fault handling
Energy Efficiency
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Significant part of OPEX
•
Included Market, regulatory and customer requirements (especially for small cells)
 Interoperability
 Interworking nodes between different networks
A tier-1 operator in Europe typically spends around 60% of revenue in OPEX. The burden will surely increase
with LTE and LTE-A
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7. Network Manageability
 The number of network nodes go-up exponentially
 Besides they co-exist with multiple other RATs
 Extremely challenging to maintain and optimize such networks e.g.
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•
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# Neighbor Relationships grow exponentially
# Handover Relationships grow exponentially
Coverage / Capacity trade-offs between different network layers
Interference management becomes even more challenging
Dynamic traffic patterns and low base station utilization
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Residential areas in the evening, Commercial during the day
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8. The Backhaul Challenge
Increasing radio network complexity casts its shadow on the backhaul
 More base stations, more backhaul links
 Base stations differ in terms of capacity, reach, transmission power and
radio access network technology, including 3G, “4G” and Wi-Fi
• Puts additional complexity burden on backhaul
 ICIC and CoMP (Coordinated Multipoint) – Needed for better user
experience at cell edge
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ICIC – Coordination of spectrum allocation across multiple cells
CoMP - Multiple base stations simultaneously serve a user device
Needed - Real time co-ordination between base stations
Needed - Low latency on backhaul
 Base station need sub-frame level co-ordination
• Clocks need to be in phase
• Common reference needed from backhaul
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9. User Device Challenge
Carrier Aggregation
 UE to handle multiple simultaneous transcievers
 Contiguous and non-contiguous carriers may be aggregated
 Challenging radio environment
MIMO
 Up to 8 transmitters in DL
 MIMO increases the number of system antennas
 Design of
• Radio antennas supporting Multiband and MIMO
• In the tiny space on a UE
• Becomes extremely challengig
 Battery life of devices
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10. Interference Management
 Higher base station density, more Interference
 Randomly distributed
• Difficult to control and maintain coverage area, tilt, power and placement of
small form factor base stations
 Particularly difficult to optimize Cell Edge users performance
• Terminal assigned to macro, sees strong interference from micro
• Especially if micro serves a CSG and the UE is not allowed to latch on to it
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11. WiFi and Offload Considerations
 Almost ubiquitous availability of WiFi (especially indoors in homes and
offices) mandates it for operators to consider offload
 Offload however comes with its own challenges that have no answer in
the specifications yet
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Pre-mature WiFi selection
Improper choices
Degraded QoS after movement to WiFi
Managing Trusted/Non-trusted networks
Ping-pong problem
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12. Evolving LTE Network
Architectures

13. Telco SDN – The Next Wave
Mobile Networks Then
Mobile Networks Now
SDN
A network of point-topoint connections
A programmable fabric that can be
manipulated in real time to meet the
needs of the applications and systems
that sit on top of it
SDN would mean
 Network virtualization - Implementing more in software and using commoditized IT hardware
 Programmability - The ability to centrally change traffic flows, partition the networks and
provide application-level QoS.
 Separation of control and data plane
Source: Telco2.net
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14. SDN Example
Ref: Flexerasoftware.com
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15. Cloud RAN – Specific SDN use-case for the RAN
Cloud RAN – The first implementation of virtualization in RAN layer
 Separates the computing intensive baseband processing from the remote
radio deployments
 Baseband processing is pooled at a semi-centralized location
 C-RAN Enables
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Use of commodity HW to run baseband processing tasks
More fluid resource allocation.
Enables new feature implementation like CoMP and eICIC
Helps ease capacity crunch by placing radios closer to the user
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16. Cloud RAN – Architecture Possibilities
Active
Antenna
System
Centralized
Baseband
Bank
•2G/2.5 G
•UMTS
•HSPA
SON Server
•LTE eNB
•LTE-A
Common
Management
Server
IMS/
Operator Services
Optical
IP
Remote
Radio
Head
Internet
Coax
IP
Macro
Site
IP
Femto
Cells/
Wi-Fi
IP
Controllers
RAN SERVERS
on the
•GSM/GPRS
cloud
•UMTS
•UMTS Femto GW
•HeNBGW
•Wi Fi Access Gateway
Core Network
• Services are provided through optimum access technology
• Resources and coverage of a geographical area can be changed
dynamically
• SON can be used to get information for providing the necessary
configuration
• Resources are aggregated and dynamically allocated
• Reconfigurable BSs and controllers to support multiple Radio Access
technologies
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17. Mobile and Cloud Infrastructure Convergence
RRHs
SDN Network Controller
Centralized BBU Pools
Core Network entity
Network Devices in SDN Terminology
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18. Aricent eNB IPR Readiness for C-RAN Solution
ENodeB Framework
• RAN on the Cloud will need to cater to variable
capacity requirements and host multiple cells.
Aricent Layer 3 and Layer 2 including Scheduler,
MAC, RLC, PDCP, GTPU, are scalable for multicore architectures, supports multiple form-factors
(femto, pico,micro) and different capacity
requirements based on deployment.
• Single instance of Aricent Layer 3 can handle
multiple cells/sectors hosted on Cloud RAN
equipment and can interface with cells/sectors
hosted on other Cloud RAN equipment on X2
link.
OAM & SON
Client
RRM
RRC,S1-AP,X2-AP
Schedul
er
PDCP,
RLC,MA
C
GTPU
• Aricent Layer 2 can handle one cell/sector per
instance and multiple instances of Layer 2 can be
utilized to handle multiple cells/sectors.
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19. Cloud Ready Aricent EPC Framework
Router
eNodeBs
Top of Rack
Switch
Top of Rack
Switch
MMEs
HSS
SGWs
PCRFs
Subnet 1
Subnet 2
Integrated software offerings for MME,
Serving GW, PDN GW, HSS and
PCRF nodes for OEMs developing
cloud EPC solutions – running in
clusters across virtualized hardware
with separated routing tables
PGWs
ISP 2
EPC Frameworks
Cloud Enablers
Multi-tenant solution
Scalable deployments
EPC on virtualized environment
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20. Summary
The promise of SDN and C-RAN: Mobile and Cloud Infrastructure Convergence
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Significant improvements in the manageability and flexibility of the network
Prevent the networks from becoming prohibitively expensive to deploy
Easy scalability
Helps in the addition of new services without the need to add more hardware
Easier for operators to exploit revenue opportunities
Meet time-to-market challenges
Helps reduce CAPEX and OPEX needs
Ability to tailor the network "on demand" to customer needs
Automated traffic management
Improved bandwidth engineering
SDN and C-RAN are the helping hands that will help LTE realize its true potential
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21. Confidentiality Statement
Confidentiality
•This material contains information that is confidential and proprietary to Aricent.
•Recipient may not distribute, copy, print or repeat information in the document
Legal Statement
•This presentation sets forth Aricent’s current thought and is subject to change at
any time without notice. Aricent is not liable for any direct or intended commitments
as may be inferred from the ensuing presentation.
•All information shared in this document is covered under a mutually signed NonDisclosure Agreement.
Proprietary & Confidential. ©Aricent Group 2013 21