BACKHAUL CONSIDERATIONS FOR LTE AND LTE-ADVANCEDENHANCE QUALITY OF EXPERIENCE AND STREAMLINE OPERATIONS WITH ALCATEL-LUCENT MOBILE BACKHAULAPPLICATION NOTE

ABSTRACTThe mobile radio access network (RAN) is evolving rapidly, driven by the need to improve capacity and coverage while keeping capital and operating expenses under control. As cell sites are rolled out in support of Long Term Evolution (LTE) services, and the increase in mobile data services continues unabated, bandwidth requirements will continue to climb. LTE, and particularly LTE-Advanced (LTE-A), bring a number of enhancements to the radio domain, that will help operators address the growing demand for bandwidth. However, they also place specific requirements on the backhaul network.

This paper examines the impact of LTE and LTE-A on mobile backhaul networks and looks at the network requirements these technologies introduce. The Alcatel-Lucent Mobile Backhaul Solution is described and the utility of its attributes in supporting efficient LTE and LTE-A deployment is highlighted.

TABLE OF CONTENTS

Impact of LTE and LTE-A on Mobile Backhaul / 1

Overview of Backhaul Requirements for LTE and LTE-A / 2

Alcatel-Lucent Mobile Backhaul Solution for LTE and LTE-A / 3

Solution overview / 3

Key solution attributes / 3

Some Deployment Scenarios / 8

Extending a mobile backhaul deployment / 8

Adding a small cell broadband backhaul deployment / 9

Conclusion / 9

Appendix: Key products in the Alcatel-Lucent Mobile Backhaul solution / 10

Alcatel-Lucent 7705 Service Aggregation Router / 10

Alcatel-Lucent 7210 Service Access Switch / 11

Alcatel-Lucent 9500 Microwave Packet Radio / 11

Alcatel-Lucent 7750 Service Router / 11

Alcatel-Lucent 5620 Service Aware Manager / 12

Acronyms / 13

Backhaul Considerations for LTE and LTE-AdvancedALCATEL-LUCENT AppLICATION NOTE

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ImpACT OF LTE AND LTE-A ON mOBILE BACKHAULLong Term Evolution (LTE) radio technology is bringing spectral efficiency improvements, supporting higher traffic volumes, and driving the shift in backhaul architectures to an all-IP model. LTE-Advanced (LTE-A) will bring further efficiencies and advanced radio signal processing techniques to boost throughput still further. Several features are particularly relevant in defining the incremental architectural and engineering requirements of the backhaul network as it evolves to support LTE and LTE-A.

Carrier aggregation delivers higher traffic rates by combining spectral bands, even if non-contiguous, into a larger aggregated carrier. In combination with higher order Multiple Input Multiple Output (MIMO) antenna technology, this has the potential to unlock very high speeds (Gb/s), particularly in the downlink.

The X2 interface from the eNodeB is a fundamental concept of LTE. The X2 interface allows meshing to take place directly between eNodeBs. This keeps certain traffic streams such as Radio Resource Management (RRM) from being unnecessarily directed to the core and back, thus improving latency and reducing network load. Initially the X2 interface was rarely activated in real-world LTE environments. However, this is starting to change as its potential efficiencies are understood and valued.

Interference mitigation is a technology focus area of LTE-A. The two principal techniques employed are Enhanced Inter-cell Interference Co-ordination (eICIC) and Coordinated Multipoint (CoMP). eICIC specifically minimizes interference between cells, often in a heterogeneous (macro and small cell) network. It does this by arranging relative power levels in adjacent cells appropriately in real time to maximize RAN performance. CoMP is a suite of techniques that can be used to mitigate interference. However, it also enables better utilization of network resources by leveraging several base stations at once and combining base station power for improved performance and quality of experience (QoE). The nature of technologies such as CoMP and eICIC means that close coordination is needed between the base stations involved.

Evolved Multimedia Broadcast Multicast Service (eMBMS) provides an efficient mechanism for the delivery of broadcast and multicast services. While eMBMS was first defined for LTE, it has been further refined and enhanced for LTE-A. eMBMS offers more carrier configuration flexibility, higher video resolution services because of higher LTE bit rates, and a dynamic reservation/release of network resources.

The emergence of public-access small cells to enhance capacity and coverage is really a parallel trend to the deployment of LTE and LTE-A rather than something formally linked to these technologies. However, it is a relevant discussion point here as it is likely to happen over the same time frame as these technologies are deployed. The heterogeneous network (or HetNet) consists of both traditional macro cells and small cells. Small cells are deployed much more densely and in higher quantities, in both outdoor and indoor urban locations with varied access to backhaul transport facilities.

Backhaul Considerations for LTE and LTE-AdvancedALCATEL-LUCENT AppLICATION NOTE

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OVERVIEw OF BACKHAUL REqUIREmENTS FOR LTE AND LTE-A It is important to ensure that the mobile backhaul network is positioned to support and complement the evolution to LTE and LTE-A. The mobile backhaul network must not be a barrier to increasing capacity and coverage and to the delivery of an optimal QoE for the end user as LTE and LTE-A are deployed. The principal requirements include:

Scalability: The backhaul network must scale smoothly to support increasing numbers of cell sites at higher capacities. LTE and LTE-A are driving the transition to an all-IP, any-to-any mobile backhaul network, leveraging MPLS for precise traffic engineering and IP-optimized transport over a highly scalable Ethernet infrastructure. Network resiliency is crucial to supporting the subscribers QoE. In particular, as more cell sites home in on higher capacity head-end systems, scalable failure recovery mechanisms become more critical to limit the breadth of impact should network resources become unavailable.

Flexibility: The introduction of a mix of small cells and macro cells in an LTE/LTE-A environment brings the need to leverage the closest, most cost-effective backhaul access infrastructure that can meet quality of service (QoS) requirements. This will result in a greater diversity in backhaul access types, driving a requirement for more flexible solutions that can operate consistently whether over microwave, xDSL, Ethernet or GPON. In addition to LTE and LTE-A, support for 2G, 3G, LTE and Wi-Fi services is needed. Mobile network operators must be able to provide appropriate access to network resources, such as link bandwidth, for a range of traffic streams, especially when networks are operated at high utilization levels. Traffic streams may include operations, administration and management (OAM); telemetry; streaming video; and voice over Internet Protocol (VoIP). Maintaining frequency synchronization has always been a requirement in networks generally and particularly in mobile. This will continue. LTE and LTE-A in particular also demand accurate phase synchronization to support video broadcast, interference management and time division duplexing for example.

Simplicity: Simplified operations are required to minimize the total cost of ownership (TCO) and permit efficient network deployment, administration and maintenance. A standardized approach to cell site backhaul provisioning and turn-up is required, regardless of access type or location. The need for site visits must be minimized. End-to-end visibility and control of elements at every cell site (macro and small) is needed for streamlined OAM, with surgical remote troubleshooting. It is crucial that the network actively indicate when key performance indications (KPIs) are out of bounds and service level agreements (SLAs) are not being met.

These requirements for LTE and LTE-A backhaul build upon the existing requirements for 2G, 3G and Wi-Fi backhaul. The Alcatel-Lucent Mobile Backhaul solution is targeted at meeting these requirements and provides a solid business foundation for efficient growth. The solution incorporates:

Service-rich IP routing, leveraging MPLS for determinism and traffic engineering

IP-optimized transport over a highly scalable Ethernet infrastructure

Backhaul Considerations for LTE and LTE-AdvancedALCATEL-LUCENT AppLICATION NOTE

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ALCATEL-LUCENT mOBILE BACKHAUL SOLUTION FOR LTE AND LTE-ASolution overviewThe Alcatel-Lucent Mobile Backhaul solution is comprised of a suite of products, and is complemented by Alcatel-Lucent professional services. The principal product elements are the Alcatel-Lucent 7705 Service Aggregation Router (SAR), the 7210 Service Access Switch (SAS), the 9500 Microwave Packet Radio (MPR), the 7750 Service Router (SR) and the 5620 Service Aware Manager (SAM).

7705 SAR

7705 SAR-O

CPRI FRONTHAUL

MICROWAVE

INDOOR SMALL CELL

BROADBAND AND ETHERNET

7705 SAR-H

7705 SAR7210 SAS

7705 SAR

9500 MPR-s

9500 MPR-s(NLOS)

(LOS)

9500 MPR-e

7705 SAR7210 SAS

7705 SAR

BBU

9500 MPRMetro

aggregationand transport

GPON/xDSLmetro Ethernet

Controllers/gateways

End-to-end Service Aware Management (5620 SAM)

7750 SR

Key solution attributesThe Alcatel-Lucent Mobile Backhaul solution leads the industry in its ability to deliver scalable, flexible and simplified backhaul networking while ensuring the resiliency, QoS and network synchronizat