High-Speed Downlink Packet Access
More efficient and cost-effective use of precious bandwidth
HSDPA makes access to sophisticated mobile IP multimedia services a reality for UMTS carriers.
This white paper addresses:
• The need for HSDPA • How HSDPA works • How to upgrade • The future
Introduction
The increasing availability of a broad range of new high-speed data services is fuelling demand for more bandwidth in order to improve the user experience, especially over mobile networks. High-speed downlink packet access (HSDPA) technology is a cost-efficient upgrade to current UMTS systems and promises to deliver performance comparable to today’s wireless LAN services, but with the added benefit of mobility and ubiquitous coverage. The new technology offers mobile operators significantly improved data speeds, increased capacity and a very real competitive edge against fixed wireless broadband providers.
What is it?
HSDPA is an upgrade to current UMTS networks that, inevitably, has already been dubbed a ‘3.5G’ technology in recognition of its advanced capabilities. HSDPA is the key feature of the 3GPP’s Release 5 specification that was approved in 1999. Major advantages include: • Peak data rates of up to seven times higher than those in the most advanced UMTS networks today • A four-fold improvement in network capacity • Reduced round-trip time between network and terminal • Sophisticated scheduling allowing favorable allocation of resources HSDPA is an asymmetric solution that enables much faster downstream throughput (i.e., network to terminal) than upstream, improving spectrum efficiency. Although the theoretical maximum data transfer speed of HSDPA is 1014Mbps, the technology will deliver a 2 – 3Mbps downlink on average. Shared among users in an adequately covered area, this will provide each user with a 300K – 1Mbps downlink, ie. comparable to current wireless LANs and domestic fixed line broadband. Uplink will be 128Kbps – double that of current UMTS systems.
Why do we need it?
Operators and the investment community know that for the UMTS business model to work, mobile data subscription rates have to grow profitably and exponentially; for example, the cost to deliver a 10Mbyte file with HSDPA would be one-fifteenth the amount that it would take to deliver the file via GPRS and one-fifth of the cost to send the same file via UMTS Release 99.
Cost to Deliver10 MMByte File Cost to Deliver 10 byte File
Cost Cost
R99 R99
HSDPA HSDPA
1
Operators must also ensure they can adequately support their new service portfolios with minimal capital expenditure. The main drivers for higher performance mobile networks include the need for: • More efficient access to office applications and a response to commercial pressure to replicate LAN experience on the move • A fixed-line broadband alternative that can support new consumer services – e.g., interactive gaming, voice over IP and SIP-based multimedia • A competing service-offering to succeed EDGE in GSM markets and counter EV-DO/DV in CDMA markets • A more efficient technology to reduce the cost of the on-going network growth • A technology that lowers the cost per byte for data and VoIP services How often do you think you would use these services?
Portable Home Travel Security Agent Every Day Every Other Day
Live Wire
Activity Agent
More Than Words
My Mobile Planet
Once A Week Less Than Once A Week
2-3 Times Per Week
Such demands mean that in the very near future, operators will need mobile networks that offer advanced quality of service capabilities and data speeds that rival those delivered by wireline networks, such as DSL and Cable Modem services. In addition, the emerging service environment will be one in which capacity can never be taken for granted. A major advantage of HSDPA is that it enables operators to significantly increase capacity in a cost effective manner. Operators that adopt the technology can benefit from more cost-effective networks and a chance to seize market share in the lucrative enterprise sector. The commercial significance of the HSDPA advantage cannot be underestimated.
2
How does it work?
In a UMTS network, the base station (known in a UMTS network as a Node B) is a transmission and reception station that acts as the access point for the user to the network and handles network traffic; the radio network controller (RNC) has overall control of the resources in the Node Bs and is also responsible for handovers in the network; the serving and gateway nodes handle and route packet switched data traffic while the mobile switching centre handles circuit switched traffic (e.g. voice or video conferencing). HSDPA is primarily implemented in the Node B and the RNC. The technology minimizes transmission delays in the network by placing key processing at the base station and thus closer to the air interface and the user. The new technology also introduces an additional transport channel called the highspeed downlink shared channel (HS-DSCH). This is a major innovation, since compared to today’s UMTS technology it improves network performance by enabling several users to share the entire downlink channel. HSDPA employs a technique called adaptive modulation and coding (AMC). This means the base station now takes data packets and schedules their transmission to a user by matching the user's priority and estimated channel operating environment with the appropriate coding and modulation scheme. This maximizes capacity and ensures all users benefit from the best possible data rate. Finally, HSPDA provides re-transmission mechanisms for faster error correction. In a spread spectrum network, it’s the role of the user device to both acknowledge the receipt of data and communicate key information relating to issues like channel condition and power control back to the Node B. With HSDPA, when a base station despatches a data packet to a handset, the Node B then waits for an acknowledgement. If it does not receive one within a prescribed time, it assumes that the data packet was lost and retransmits it. In short, the driver behind this upgrade is the provision of optimum bandwidth for all users coupled with the best possible channel conditions.
How do you upgrade?
HSDPA is routinely described as a simple upgrade to existing UMTS infrastructure. However, as is so often the case with these ‘simple’ upgrades, the majority of vendors claim their systems are ‘HSDPA-ready’ and the reality is that some are considerably more ready than others. Lucent recognised the cost and efficiency benefits of HSDPA technology at an early stage. As a result Lucent’s UMTS systems require only a software upgrade to support HSDPA. However, not all the hardware currently deployed from other vendors will be capable of handling the new requirements, hence the need for costly replacements, not just upgrades. In order to support the new modulation schemes associated with HSDPA, modifications are required to the Node B channel cards and to the devices in the radio path (amplifiers and
3
transmitters). The channel card must also be able to handle the scheduling, buffering, transmission and retransmission of data blocks that are received from the RNC.
What about terminals?
Historically, lack of terminals has acted as a constraint to the widespread adoption of new wireless technology. Everyone assumes the same will be true of HSDPA-enabled devices, but the fact is that suitable PC cards will be available in time, in sufficient quantities. These will precede conventional handsets as it is undoubtedly proving easier to fit the technology on to less space constrained devices, added to which power supply for notebooks is less of a concern than for normal phones. As a key element of its UMTS offering, Lucent is working with its partners to introduce HSDPA data cards at the same time as the first commercial upgrades to the infrastructure are released in 2005.
Where and why?
It seems certain that eventually every UMTS market will see HSDPA deployments - the technology offers operators too much of an edge to be ignored. However, the circumstances of individual operators and the competitive environment in specific markets will determine the urgency of deployment. Greenfield operators could see HSDPA as a means of seizing market share from more established competitors. HSDPA could be the means through which established players hold their own in aggressively competitive markets. Fierce competition in the Japanese market is certainly one of the reasons NTT DoCoMo has been among the first to trial the technology - coupled, of course, with the company’s insatiable thirst for innovation. In a dense, multimedia hungry market like Japan, DoCoMo will also have an eye on the very considerable capacity gains offered by the new technology. As far as Europe is concerned, at the 3GSM World Congress 2004, HSDPA had clearly shifted up the agenda of every major European player. Capacity gains are clearly important, along with the ability to offer a comprehensive suite of advanced data services. In the USA, GSM carriers are certainly looking for more ammunition to keep ahead in an increasingly aggressive market. Cingular for instance announced in May 2004 that it was testing HSDPA capabilities as part of its UMTS trials with Lucent in Atlanta.
4
The future
HSDPA is a critical first step in enhancing W-CDMA network performance. However, there are already plans afoot to push the technology further. The next two major features of 3GPP’s Release 6 and 7 specifications are an up-link improvement solution called enhanced up-link dedicated channel (EU-DCH) and throughput increases through multiple-input, multiple-output (MIMO). While HSDPA is about maximizing downlink performance, EU-DCH is being developed to improve uplink-intensive services or applications requiring a balanced link like interactive video or voice over IP. EU-DCH will also reduce latency and facilitate the efficient use of TCP/IP applications like Microsoft Outlook over mobile networks.
Industry perspective
One of the technology’s many supporters at the 3GSM World Congress was Vodafone CEO Arun Sarin. ‘When W-CDMA comes in its full form, in 2004/05, we’ll see a sea change in what products we can offer, and with HSDPA we’ll offer even more,’ he told delegates. HSDPA also received a ringing endorsement from O2 CEO Peter Erskine. ‘To us, HSDPA-enhanced UMTS looks like real 3G,’ he explained in a recent interview. ‘It offers very high bandwidth, which in turn means customers can have a premium service without the hassle and costs involved in ADSL type solutions. HSDPA means we can deliver a genuine wireless broadband experience to our customers. In the USA, Cingular’s acting CTO Kris Rinne, commenting on the Atlanta trial with Lucent said: ‘This trial offers us an ideal opportunity to evaluate the capabilities and range of services that we can offer to our customers using UMTS and HSDPA technology, and overcome technical challenges before pursuing broader deployments.’ In recent reports, analysts PA Consulting and the Yankee Group have both argued that the demand for the high-speed data rates enabled by HSDPA is likely to come from the enterprise market in the first instance. PA Consulting’s Alan Carr believes HSDPA is central to the business case for UMTS in the enterprise space. He also suggests that, with some 70 per cent of such users inside buildings, it could be that HSDPA-enabled picocell base stations have a key role to play servicing this market. The Yankee Group sees HSDPA as an important differentiator that enables operators to market premium service provision in the enterprise space. Yankee's John Jackson is convinced HSDPA technology has a prominent role to play in the transition to significantly faster 3G service offerings. ‘It's going to be an acronym that we'll be getting very familiar with,’ Jackson said recently.
5
The Gartner Group has focussed on the network efficiency implications of HSDPA deployments. ‘HSDPA allows operators to dramatically increase the number of higher data rate users on the same radio carrier signal — significantly improving the economics,’ explains wireless analyst Jason Chapman. Gartner also suggests operators that deploy HSDPA will have considerable competitive advantage in their markets. ‘HSDPA allows W-CDMA to deliver a true wireless broadband experience at a cost per Mbyte one ninth that of GPRS,’ says Chapman. ‘This will allow operators to cut prices dramatically.’
Conclusion
HSDPA is an extremely cost-effective path to higher data rates and provides more efficient use of valuable spectrum. It enables operators to compete effectively in increasingly converged markets and satisfy the need for enhanced QoS and bandwidth-hungry services in an efficient and costeffective manner. Today’s markets are hugely competitive. User expectations are formed by their increasing experience with fixed, cable, LAN and wireless networks. HSDPA makes access to sophisticated mobile IP multimedia services a reality for UMTS carriers. With its peerless experience optimising spread spectrum networks, its key role in the development of the relevant standards and the pioneering work of Bell Labs, Lucent is leading the way in bringing a significant competitive advantage to its operator partners.
6
Response Centers: EMEA and Asia Pacific Email: mobility@lucent.com NAR/CALA Tel: +1 888 426 2252 This document is for planning purposes only and is not intended to modify or supplement any specifications or warranties or tariffs relating to these products. Any technical specifications contained herein are approximate and subject to change without notice.
Lucent is a world-class supplier of mobility solutions. Innovation is at the heart of our business. Our Centers of Excellence and the global facilities of Bell Labs, are shaping the way our world communicates. We offer unchallenged market leadership in CDMA radio access, the underlying technology for UMTS/W-CDMA, ATM backbone networking technology, circuit and packet switching as well as the expertise to integrate and deploy complex networks. Call Lucent for complete end-to-end mobility solutions or visit our website at www.lucent.com
Brochure No: HSDPA WP 11.2004 © 2004 Lucent Technologies. All rights reserved.