HSPA+LTE Carrier Aggregation 6.26.12 - 5gamericas :: en 4G Americas HSPA+LTE Carrier Aggregation – June 2012 EXECUTIVE SUMMARY LTE networks are being rolled out at an increasing

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  • 1 4G Americas HSPA+LTE Carrier Aggregation June 2012

    TABLE OF CONTENTS

    Executive Summary ...................................................................................................................................... 2

    1. Introduction .............................................................................................................................................. 3

    1.1 Scope .................................................................................................................................................. 3

    1.2 HSPA+ and LTE network deployment projections .............................................................................. 3

    2. Multicarrier and multi-radio network evolution ......................................................................................... 6

    2.1 Spectrum and deployment aspects ..................................................................................................... 6

    2.2 HSPA evolution from multiple carriers to multicarrier .......................................................................... 8

    2.3 LTE Evolution from multiple carriers to carrier aggregation .............................................................. 13

    2.4 HSPA and LTE interworking .............................................................................................................. 16

    2.5 HSPA+LTE carrier aggregation ......................................................................................................... 18

    3. Benefits and use cases of HSPA+LTE aggregation .............................................................................. 19

    3.1 Benefits of HSPA+LTE aggregation .................................................................................................. 19

    3.2 Example USE cases for HSPA+LTE Aggregation ............................................................................ 20

    4. HSPA+LTE aggregation system architecture considerations ................................................................ 21

    4.1 Service or core network level split/merger ........................................................................................ 23

    4.2 HSPA RAN level split/merger ............................................................................................................ 25

    4.3 LTE RAN level split/merger ............................................................................................................... 28

    5. Practical implementation aspects of HSPA+LTE aggregation ............................................................... 30

    5.1 Base station Radio implementation aspects ..................................................................................... 30

    5.2 Device Radio implementation aspects .............................................................................................. 31

    5.3 Implementation aspects other than radio processing ........................................................................ 33

    6. Conclusion ............................................................................................................................................. 34

    Abbreviations .............................................................................................................................................. 35

    Acknowledgements ..................................................................................................................................... 37

  • 2 4G Americas HSPA+LTE Carrier Aggregation June 2012

    EXECUTIVE SUMMARY

    LTE networks are being rolled out at an increasing speed, while at the same time the existing HSPA networks are expanded and upgraded with the more advanced HSPA+ features in order to cater to the ever-increasing appetite for wireless data. Due to the major investments in the HSPA+ infrastructure and the vast and rapidly increasing HSPA+ based mobile broadband device penetration the two networks can be foreseen to coexist in parallel for years to come.

    The evolution of both HSPA+ and LTE standards has introduced aggregation of carriers for higher data rates, better load balancing and increased spectrum utilization, and since the dawn of LTE, the standard support for radio level interworking for HSPA and LTE radios has been included. A natural continuation of such development is to tighten the interworking even further and introduce similar aggregation of carriers between the two radio access technologies.

    The HSPA+LTE aggregation allows for transmitting data to one user simultaneously using both the HSPA and the LTE radios for maximal utilization of the available spectrum and the deployed equipment. This is considered beneficial especially in the environment where the spectrum that needs to be shared between the two radio access technologies is not abundant, and the deployed HSPA and LTE capacities and user data rates suffer from spectrum crunch. One example of such deployment is the 900 MHz for HSPA and the 800 MHz for LTE which are both seen attractive bands for building the coverage due to the low frequency but also suffer from very limited spectrum availability. With aggregation of the two bands it is possible to provide the high data rates expected from the LTE services while at the same time maintain coverage for the HSPA devices.

    The same gain mechanisms that have been seen beneficial for Multicarrier HSDPA as well as LTE Carrier Aggregation can be benefited from by aggregating HSPA with LTE. At low or medium load, HSPA+LTE aggregation is able to take advantage of the unused resources leading to significant data rate increases both at the cell edge and the cell center for the carrier aggregation capable devices. In addition, the carrier aggregation enables fast (millisecond level) load balancing across the carriers thus improving the data rates of all users.

    A number of possible network architectures can be foreseen for HSPA+LTE aggregation, and are briefly touched upon in this white paper. Most promising architecture options are seen with co-located multiradio base stations with the base station (NodeB + eNodeB) acting as the data aggregation point, and simultaneously maintaining the existing network architecture for the devices connecting to the network with one radio system at a time only. This architecture can utilize some of the already deployed RF hardware in the base station, while new baseband functionality managing the data flow is required. On the device side, receiver radio architectures capable of multiband carrier aggregation should be suitable also for HSPA+LTE aggregation.

    While Dual-Cell HSDPA is already in commercial operation, and higher levels of HSPA carrier aggregation as well as LTE carrier aggregation are part of 3GPP specifications existing today, HSPA+LTE aggregation is currently not standardized. Although conceptually straightforward and building on already standardized concepts, HSPA+LTE aggregation is a major feature, with a standardization effort comparable to that of LTE carrier aggregation.

  • 3 4G Americas HSPA+LTE Carrier Aggregation June 2012

    1. INTRODUCTION

    1.1 SCOPE

    This white paper will highlight some of the key aspects and architecture options available for aggregating HSPA and LTE carriers. Individually within both the HSPA and the LTE evolution, downlink and uplink carrier aggregation as well as co-site and inter-site aggregation have been considered. For both radio access technologies, the co-site aggregation has been standardized first and inter-site aggregation is currently being worked on.

    The HSPA+LTE aggregation is a potential 3GPP Release 12 topic, and at the time of writing, there is yet no official commitment or ongoing work related to any Release 12 items ongoing in the standards body. Hence the contents of this white paper can be seen more as visionary and exploratory than describing a feature already existing, or being worked on in the standard.

    1.2 HSPA+ AND LTE NETWORK DEPLOYMENT PROJECTIONS

    HSPA, HSPA+ AND LTE DEPLOYMENTS AS OF JUNE 2012

    HSPA: 473 commercial networks in 180 countries HSPA+: 227 commercial networks in 109 countries LTE: 91 commercial networks in 47 countries LTE: 335 operator Commitments worldwide LTE: Over 130 commercial networks expected by year end 2012

    4G AMERICAS WHITE PAPER THE EVOLUTION OF HSPA OCTOBER 2011

    Whereas, LTE has tremendous momentum in the marketplace and it is clearly the next generation OFDMA based technology of choice for operators gaining new spectrum, HSPA will continue to be a leader in mobile broadband subscriptions for the next five to ten years. Some forecasts put HSPA at over 3.5 billion subscribers by the end of 2016, almost five times as many LTE subscribers predicted. Clearly, operators with HSPA and LTE infrastructure and users with HSPA and LTE multi-mode devices will be commonplace. With the continued deployment of LTE throughout the world, and the existing ubiquitous coverage of HSPA in the world, HSPA+ will continue to be enhanced through the 3GPP standards process to provide a seamless solution for operators as they upgrade their networks.

    High-Speed Packet Access (HSPA) systems are now commonplace across Latin America and operators are looking to get full benefit from this technology as it evolves to HSPA+. Although the future is LTE, the region is a good example of how 3G networks can take the customer all the way to the cusp of that new era. Progress made since 3GPP Release 7 has allowed HSPA+ to benefit from the techniques used in the elaboration of LTE to ensure that both support smart phones, tablets and PCs as user needs grow.

    The 4G Americas white paper T