HSPA Whitepaper

HSPA+ for Enhanced Mobile Broadband

Qualcomm Incorporated February 2009

Release 7 HSPA+ For Mobile Broadband Evolution

2/2009 page i

Table of Contents

[1] Executive Summary ......................................................................... 1

[2] Introduction and Overview ............................................................... 2

2.1 What is HSPA+?...................................................................... 3

[3] HSPA Offers an Entire Range of IP Services .................................. 4

[4] HSPA+ Doubles Data Capacity and Reduces Cost ........................ 4

4.1 Multiple Input Multiple Output (MIMO)..................................... 5

4.2 Higher Order Modulation (HOM) ............................................. 6

4.3 Discontinuous Transmission and Reception (DTX/DRX)........ 6

[5] HSPA+ More than Doubles the Voice Capacity .............................. 7

5.1 Higher Data Capacity through Voice over HSPA .................... 8

[6] Enhanced User Experience Benefits ............................................... 9

[7] Multicarrier Further Enhances the Broadband Experience............ 10

[8] HSPA+ is the natural evolution of HSPA at a lower cost............... 12

[9] The Optimal Solution in single and aggregated 5 MHz blocks ...... 13

[10] HSPA+ Has a Strong Evolution Path beyond R8 ........................ 15

[11] Conclusion ................................................................................... 16

[12] Appendix ...................................................................................... 17


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[1] Executive Summary WCDMA operators have rapidly launched High Speed Packet Access (HSPA) services to capitalize on HSPA’s mobile broadband capabilities and increased data capacity. As the natural evolution, HSPA+ further enhances the mobile broadband experience and increases the capacity through incremental investments and backward compatible handsets. HSPA+ Release 7 (R7) is commercial and HSPA+ R8 is targeted for commercialization during 2010. HSPA+ has a strong evolution path beyond HSPA+ R8 and the definition of HSPA+ Release 9 (R9) has already started in the 3GPP standards.

HSPA+ R7 doubles the data capacity of HSPA and more than doubles the voice capacity WCDMA, enabling operators to offer mobile broadband and voice at even lower cost. HSPA+ Release 8 (R8) introduces the first step of the multicarrier feature, aggregating two 5 MHz carriers, which doubles the user data rates to all users in the cell. While HSPA already supports the full range of packet-based IP services with integrated Quality of Service (QoS), HSPA+ further enhances the end-user experience through higher peak rates, lower latency, improved “always-on” experience and extended talk time. HSPA+ is the optimal solution for single or aggregated 5 MHz carriers and provides performance similar to that of LTE in the same bandwidth and when using the same number of antennas. HSPA+ is the natural evolution of HSPA and provides next-generation performance through an incremental and a cost-effective upgrade while leveraging existing investments.


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[2] Introduction and Overview Nearly all WCDMA operators across both developed and developing countries have rapidly launched HSPA services to capitalize on its excellent mobile broadband capabilities and increased data capacity. The enhanced downlink (HSDPA) had been launched commercially by 217 operators in 93 countries as of early 2009.The enhanced uplink (HSUPA) is also quickly being introduced with around 50 deployments as of early 2009. HSPA devices have proliferated and mobile operators have seen data services account for a rising and substantive proportion of their revenue. HSPA+ is the natural evolution of HSPA and operators are now preparing to commercially launch HSPA+ R7 in early 2009. HSPA+ R7 is the first evolutionary step beyond HSPA and HSPA+ R8 is targeted for commercialization during 2010 with multicarrier as a key feature. HSPA+ further enhances the mobile broadband experience and increases the voice and data capacity of HSPA. This white paper discusses the HSPA+ key benefits:

HSPA+ enhances mobile broadband with data rates up to 42 Mbps in R8 while R7 enables up to 28 Mbps downlink data rates.

HSPA+ doubles the data capacity over HSPA and more than doubles voice capacity over WCDMA, reducing the cost of delivering voice or data services (more efficient voice over HSPA+ can also be used to free up data capacity).

HSPA+ enhances the end-user experience with lower latency, faster call set-up time, improved “always-on” experience and a longer talk time.

HSPA+ multicarrier further enhances the broadband experience. HSPA+ R8 doubles the data rates to all users and can significantly increase the bursty application capacity, e.g., Web browsing.

HSPA+ is the optimal solution for single and aggregated 5 MHz carriers, and provides similar performance as LTE for the same bandwidth and using the same number of antennas.

HSPA+ is the natural evolution of HSPA at a lower cost, enabling an incremental and cost-effective upgrade that leverages existing assets.


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2.1 What is HSPA+? HSPA+ is the name of the set of HSPA enhancements that are defined in 3GPP beyond Release 6 (R6). The enhanced downlink (HSDPA) was defined in R5 and the enhanced uplink (HSUPA) was defined in R6.

Figure 1: The HSPA+ evolution

This paper focuses on the first and second step of the HSPA evolution and the enhancements that have been defined in 3GPP R7 and R8. For a more detailed view of the R7 and R8 features, see the appendix at the conclusion of this paper. As seen in Figure 1, HSPA+ further enhances the mobile broadband experience by providing up to 28 Mbps peak data rates in the downlink (DL) in R7, and up to 42 Mbps in R8.

HSPA+ has a strong evolution path and will continue to evolve beyond HSPA+ R8 to further enhance the HSPA+ performance and provide a clear evolution path for current HSPA networks. The definition of HSPA+ R9 was already initiated in early 2009. HSPA+ R9 and beyond is considering enhancements such as expanding HSPA+ multicarrier beyond 10 MHz deployments combined with MIMO (Multiple Input Multiple Output) to provide peak rates of 84 Mbps and more.

201 201 2012200Note: Estimated commercial dates

Created 01/14/09

2010 2011 2012+2009

WCDMA HSPARel-99 Rel-5

(HSDPA)Rel-6

(HSUPA)Rel-7 Rel-8 Rel-9 and beyond

DL: 28 MbpsUL: 11 Mbps

DL: 42 Mbps1

UL: 11 MbpsDL: 1.8-14.4 MbpsUL: 384 Kbps

DL: 1.8-14.4 MbpsUL: 5.7 Mbps

1R8 will reach 42 Mbps by combining 2x2 MIMO and HOM (64QAM) in 5 MHz, or by utilizing HOM (64QAM) and multicarrier in 10 MHz.2R9 and beyond may utilize combinations of multicarrier and MIMO to reach 84 Mbps peak rates and beyond. Similarly, uplink multicarrier can double the uplink data rates.

Note: Estimated commercial dates

DL: 84 Mbps and beyond2

UL: 23 Mbps and beyond2

Created 01/14/09

HSPA+ (HSPA Evolved)

Enhanced performance and higher data rates

2x data capacity>2x voice capacity

Broadbanduploads, QoS

Broadbanddownloads

Multicarrier- doubled data rates to all users

2010 2011 2012+2009

WCDMA HSPARel-99 Rel-5

(HSDPA)Rel-6

(HSUPA)Rel-7 Rel-8 Rel-9 and beyond

DL: 28 MbpsUL: 11 Mbps

DL: 42 Mbps1

UL: 11 MbpsDL: 1.8-14.4 MbpsUL: 384 Kbps

DL: 1.8-14.4 MbpsUL: 5.7 Mbps

1R8 will reach 42 Mbps by combining 2x2 MIMO and HOM (64QAM) in 5 MHz, or by utilizing HOM (64QAM) and multicarrier in 10 MHz.2R9 and beyond may utilize combinations of multicarrier and MIMO to reach 84 Mbps peak rates and beyond. Similarly, uplink multicarrier can double the uplink data rates.

Note: Estimated commercial dates

DL: 84 Mbps and beyond2

UL: 23 Mbps and beyond2

Created 01/14/09

HSPA+ (HSPA Evolved)

Enhanced performance and higher data rates

2x data capacity>2x voice capacity

Broadbanduploads, QoS

Broadbanddownloads

Multicarrier- doubled data rates to all users


2/2009 page 4

[3] HSPA Offers an Entire Range of IP Services HSPA and HSPA+ allows consumers and business users to rely on HSPA as their main broadband connection, and offer a similar user experience across mobile and fixed networks. HSPA’s high-capacity broadband uplink and downlink with integrated QoS and low latency can support the entire range of IP services, including delay-sensitive applications such as VoIP and low latency gaming. HSPA+ further enhances the user’s experience and makes these services more affordable by lowering costs through increased capacity.

Figure 2: HSPA supports the entire range of IP services

[4] HSPA+ Doubles Data Capacity and Reduces Cost With the launch of HSPA, operators are seeing a significant uptake in data demand, a result of new data applications and increased demand for high-performance mobile broadband services. HSPA+ enhances the performance of HSPA networks and enables wireless operators to continue to fulfill these data needs in the most economical way, as HSPA+ doubles the data capacity compared to HSPA R6.

Figure 3 compares the downlink and uplink data capacity of HSPA and HSPA+. The almost doubled downlink and uplink data capacity assumes


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advanced receivers (UE equalizer, device receive diversity and Node B IC)1 in addition to the HSPA+ features.

Figure 3: Data Capacity per Sector in Mbps (5 MHz)

HSPA greatly increased data capacity over R99 systems by adding the high-speed shared channels with HOM (16QAM), smaller transmission interval, Hybrid ARQ (HARQ) and opportunistic scheduling. HSPA+ builds on this solid foundation by adding support for 64QAM, 2x2 MIMO, DTX/DRX and other air interface improvements to enhance the capacity and the user experience.

4.1 Multiple Input Multiple Output (MIMO) HSPA+ R7 supports 2x2 downlink MIMO that uses two transmit antennas at the Node B to transmit orthogonal (parallel) data streams to the two receive antennas at the device. Using two antennas and additional signal processing at the receiver and the transmitter, MIMO can increase the system capacity and double user data rates without using additional Node B power or bandwidth. Additionally, MIMO beamforming provides gains for cell edge users where parallel MIMO streams may not be possible.

1 UE Type 3 device receiver: linear MMSE equalizer and receive diversity.


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To be most effective, parallel MIMO streams need a high signal-to-noise ratio (SNR) at the device and a rich scattering environment. High SNR ensures that the device will be able to decode the signal successfully and a rich scattering environment ensures that the two data streams remain orthogonal. The MIMO benefit is therefore maximized in a dense urban (city) environment, as there is enough scattering and cell sizes are small (potentially high SNR at the device). In rural environments with large cell sizes and less scattering, the MIMO gains will be smaller.

4.2 Higher Order Modulation (HOM) HSPA supports 16QAM modulation on the downlink and QPSK on the uplink. As Figure 4 shows, the data capacity (bits/symbol) increases as we move from QPSK to 16QAM and 64QAM. HSPA+ R7 introduces 64QAM on the downlink, which increases the data rates by 50% for devices in good signal conditions (high SNR). On the uplink, 16QAM doubles data rates for devices that are not power headroom limited.

Wireless signals transmitted with a higher modulation are more sensitive to interference and require a higher SNR at the receiver for successful demodulation. HOM significantly increases the data rates for users with high SNR. Hence, the traffic for these users can be serviced faster, leaving Node B with more time and resources to service users in weaker signal areas, such as the cell edge. Overall, this provides high data rates and improved user experience for all users in the cell.

Figure 4: Higher Order Modulation

4.3 Discontinuous Transmission and Reception (DTX/DRX) The CPC feature DTX allows the device to gate off the control channels when there is no user data to send. In the same way, DRX allows the device to turn off the receiver at certain agreed intervals in which Node B does not transmit any downlink information to the device. Synchronized DTX and DRX operation allows the device to shut off its transmitter and receiver blocks completely, which significantly improves the device battery life for voice over HSPA services. CPC also improves the ”always-on” experience by allowing users to stay longer in the connected mode without compromising battery life when using bursty applications like Web browsing. DTX also increases the uplink capacity by reducing the uplink interference, which is especially beneficial for low-rate data applications like voice over HSPA.


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[5] HSPA+ More than Doubles the Voice Capacity High-quality voice is a key service that has traditionally been the core of the wireless business. HSPA+ enables two options, CS (circuit-switched) voice over HSPA or VoIP, which both more than double the WCDMA R99 voice capacity and provide up to 50% more talk time, while maintaining the same quality and codec. Users will continue to enjoy simultaneous voice and high-speed data services while operators now can flexibly mix voice and data services on the same HSPA+ carrier. Figure 5 shows the voice over HSPA options and the more than doubled voice capacity over WCDMA.

Figure 5: Voice over HSPA more than doubles voice capacity over WCDMA

CS voice over HSPA leaves the core network intact, allowing operators to leverage their existing core network investments, while VoIP relies on the IMS core network. CS voice over HSPA is therefore the natural upgrade for most operators but could also be an intermediate step toward the long-term goal to migrate to VoIP.

In current WCDMA/HSPA networks, voice services are carried over dedicated CS bearers, which are assigned to users for the duration of the voice call. Voice over HSPA uses the shared-packet channels with smaller transmission intervals and HARQ to transfer voice packets more


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efficiently. HSPA+ further improves voice capacity by introducing enhancements such as CPC. This optimizes air-interface resource usage, providing almost double the voice capacity without Node B IC and an almost threefold increase with Node B IC.

The enhanced serving cell change (E-SCC) in R8 further improves the handover reliability with reduced dropped calls in demanding propagation environments. It also enables full voice over HSPA capacity potential by allowing the use of F-DPCH in all propagation scenarios2.

5.1 Higher Data Capacity through Voice over HSPA The more than double voice capacity increase can also be used to increase the data capacity. This is a key driver in the adoption of voice over HPSA, as it increases the data capacity and offers data services at a lower cost. Mixing voice and data on the same HSPA+ carrier is more efficient than mixing WCDMA R99 CS voice and HSPA+ data. This means that at any given voice load level, the system has significantly more data capacity if voice over HSPA+ is used instead of WCDMA CS voice. Figure 6 presents the remaining downlink data capacity for these two cases. Furthermore, voice over HSPA is typically uplink-limited, and there is additional capacity left over in the downlink at the maximum uplink voice capacity.

Figure 6: Sector Data Capacity when Mixing Voice/VoIP and Data

2Without E-SCC, signaling might have to be transported on DCH which will reduce the Voice over HSPA capacity.


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[6] Enhanced User Experience Benefits HSPA+ not only improves the user data rates for enhanced mobile broadband, it also enhances the end-user experience in other ways:

• Improved “always-on” experience by allowing user to stay longer in connected mode without compromising battery life (CPC).

• More responsive user experience thanks to lower latency with 50% reduced transition time between inactive and connected states and 50% reduced over-the-air call setup time compared with HSPA R6 (enhanced Cell_FACH/PCH).

• Up to 50% extended talk time through voice over HSPA (VoIP or CS voice over HSPA) compared to WCDMA.

CPC improves the “always-on” experience by allowing packet data users to stay in the connected mode longer without significantly compromising the battery life. A user has to move to the inactive state after some inactivity time, but CPC enables the user to stay in connected mode longer and potentially already be in connected mode when the user becomes active again. In addition, the enhanced Cell_FACH allows for 50% reduced transition time between active and inactive states. Together, these features provide an enhanced user experience with a better “always-on” experience and more responsive services.

The enhanced Cell_FACH/PCH is achieved by moving the transmission of the paging channel (PCH) and the intermediate Cell_FACH state to the high-capacity HSPA channel. This allows for higher performance and thus reduced latency. The enhancements also reduce the over-the-air call set-up time by 50%3

3 The transition time from inactive mode (Cell-PCH) to active mode (Cell_FACH/DCH).


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[7] Multicarrier Further Enhances the Broadband Experience The multicarrier feature aggregates multiple 5 MHz HSPA carriers, creating a fatter data pipe and thus providing an enhanced mobile broadband experience to all users in the cell, as depicted in Figure 7. The initial HSPA+ R8 implementation of multicarrier supports two aggregated downlink (DL) carriers that will double the user data rates to all users across the cell—all the way to the cell edge. Furthermore, the peak data rates scales with the bandwidth and doubles to 42 Mbps in the downlink in 10 MHz (without MIMO in R84).

Figure 7: Multicarrier further enhances the broadband experience

Multicarrier thus allows subscribers to enjoy an enhanced broadband experience with quicker overall network responses thanks to the higher data rates. This is especially beneficial for bursty applications like Web browsing in which the user can be served twice as fast compared to a single carrier and experience 50% reduced over-the-air latency.

4 Future releases beyond R8 may allow combination of MIMO and multicarrier. HSPA+ R8 also allows the combination of MIMO and 64 QAM to enable 42 Mbps in 5 MH.


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Figure 8: R8 Multicarrier doubles user data rates to all users in the cell5

Multicarrier is typically a cost-effective software upgrade to the Node B that allows for incremental introduction—multicarrier can be introduced in high demand areas or even single sites with seamless interoperability with single carrier deployments. Multicarrier leverages spectrum resources better through dynamic load balancing across carriers and improved trunking efficiency, creating a better network performance as data services increase. Multicarrier mainly enhances the broadband experience, but can also provide significant capacity improvement for bursty applications over partially loaded carriers.

As shown in Figure 9, multicarrier can support significantly more bursty applications users, like Web browsing, compared to two single carriers for the same user experience (latency) in partially loaded networks. Networks are not typically fully loaded all the time and multicarrier could double the bursty application capacity compared to two single carriers. A multicarrier deployment approaching a fully loaded network scenario will resemble the full buffer scenario and provide limited capacity gain even for bursty applications.

5Each scenario is based on the same total number of users per carrier. Shows peak data rata (scaled down a factor 2x) and the burst data rate for the median users and the 10% worst (cell edge) users.


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Figure 9: R8 Multicarrier capacity vs. latency tradeoff6

[8] HSPA+ is the natural evolution of HSPA at a lower cost HSPA+ provides an excellent technology evolution path from HSPA enabling operators to maximize their return on existing investments with commercial deployments starting in early 2009. HSPA+ is designed to be compatible with existing R99, R5/R6 devices and networks, and uses the same spectrum and network resources to deliver enhanced performance. The existing radio and core network can be upgraded to HSPA+ without the need for adding any new network elements. Existing WCDMA and new HSPA+ devices can roam seamlessly between WCDMA, HSPA and HSPA+ networks. Backward compatibility will enable operators to roll out HSPA+ features in phases, without concern about device/network incompatibility. Many of the HSPA+ features are software upgrades to the existing base stations.

6The bursty nature means that a multicarrier can support more users at the same response time for partially loaded carriers. The gain depends on the load and can exceed 100% for fewer users (less loaded carrier) but less for many users (starting to resemble full buffer).


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By deploying HSPA+, wireless operators will benefit tremendously from the vast 3GPP device and vendor ecosystem that provides economies-of-scale benefits to the 3GPP community. Operators have greater flexibility in selecting vendors, and have a larger choice of devices and terminals that they can potentially offer to their customers at an affordable price.

This wide vendor support and backward compatibility also enables operators to deploy HSPA+ in a timely manner and gives them a time- to-market advantage compared with other competing technologies.

Figure 10: HSPA+ Network Upgrades

[9] The Optimal Solution in single and aggregated 5 MHz blocks HSPA+ is an incremental upgrade of the existing HSPA networks, using the same spectrum and network resources. HSPA+ performance in single or aggregated 5 MHz block is comparable to LTE, using the same number of antennas.

Figure 11 shows the comparable capacity of HSPA+ and LTE in a 5 MHz system. Given the advantages of backward compatibility and superior system performance, HSPA+ is the optimal solution for upgrade of the existing HSPA networks and for new, re-farmed single or aggregated 5 MHz spectrum blocks.


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Figure 11: Downlink Data Capacity per Sector ( Mbps) and peak data rates7

3GPP is also standardizing LTE in Release 8, an OFDMA-based system supported by a new core network called EPC. Throughout the design of LTE and EPC, emphasis is placed on ensuring interoperability with existing 3GPP technologies like WCDMA/HSPA. This will ensure that HSPA+ and LTE co-exist while LTE will leverage newer, wider or TDD spectrum to provide a capacity boost in high-demand areas. Initial deployments of LTE will be best suited for urban hot spots, whereas HSPA+ will cover the existing vast HSPA footprint. Multimode devices will be used. HSPA+ will also ensure a consistent user experience across the entire network with similar performance when using the same bandwidth and number of antennas as LTE.

7Source: Qualcomm Simulation, details in 3GPP R1-070674. 500m ISD, HSPA+ results scaled up from 10 MHz, HSPA+. HSPA+: 16QAM not considered for the UL and device IC not considered for the DL. HSPA+ multicarrier and DL Interference Cancellation would further increase HSPA+.


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[10] HSPA+ Has a Strong Evolution Path beyond R8 HSPA has a strong evolution path beyond HSPA+ R8. The definition of HSPA+ R9 has already been initiated in early 2009 with focus on multicarrier enhancements. The combination of MIMO and multicarrier in 10 MHz would enable 84 Mbps in HSPA+ R9 . Uplink multicarrier is also a R9 candidate that would increase the uplink data rates to 23 Mbps, with similar benefits as downlink multicarrier within the limit of the device transmit power.

HSPA+ R8 allows aggregation within the same spectrum band only, but future enhancements may also target the aggregation across bands, even with large RF separation, allowing operators to better leverage all their spectrum assets. Aggregation of up to four downlink carriers are also being considered, enabling 84 Mbps peak data rates in 20 MHz (without MIMO).

Figure 12: Multicarrier aggregation of up to four carriers


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[11] Conclusion HSPA+ is the natural and most economical evolution from HSPA, allowing WCDMA/HSPA operators to make the most efficient use of their existing assets and investments in network, spectrum and devices at a lower cost. HSPA+ is backward compatible, allowing for a gradual introduction of devices and a smooth, cost-efficient and simple network upgrade to existing HSPA nodes. Thanks to the doubled data capacity and more than doubled voice capacity over HSPA and WCDMA, respectively, HSPA+ enables operators to offer mobile broadband and voice services at an even lower cost. HSPA+ further enhances the end-user experience through lower latency, extended talk time through VoIP, and an improved “always-on” experience.

Given the availability of HSPA+ R7 in early 2009, HSPA+ and its evolution remains the most optimal solution for existing WCDMA/HSPA operators. HSPA+ provides a proven technology with economies of scale in device and network procurement. HSPA+ has a strong evolution path; HSPA+ Release 8 (R8) is targeted for commercialization during 2010 and introduces the first step of the multicarrier feature which further enhances the broadband experience by doubling the user data rates to all users. HSPA+ is therefore the optimal solution for single or aggregated 5 MHz carriers and provides similar performance as LTE in the same bandwidth and when using the same number of antennas.


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[12] Appendix

Table 1: Key HSPA+ R7 Features

Table 1presents the key HSPA+ R7 features and their benefits. In addition to the HSPA+ enhancements defined in the 3GPP standards, we anticipate that interference cancellation (IC), both in the uplink (Node B IC) and downlink (UE IC) will be introduced in a similar timeframe as HSPA+. Thus, the performance numbers discussed in this paper assume implementation of Node B IC. Error! Reference source not found.presents the key HSPA+ R8 features and their benefits.

Table 2: Key HSPA+ R8Features

© 2007 Qualcomm Incorporated. All rights reserved. Qualcomm asserts that all information is correct through February 2009.

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HSPA Whitepaper