High-Speed Downlink Packet Access
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High-Speed Downlink Packet Access (HSDPA) (Sometimes known as High-Speed Downlink Protocol Access) is a 3G mobile telephony protocol in the HSPA family, which provides a roadmap for UMTS-based networks to increase their data transfer speeds and capacity. Current HSDPA deployments now support 1.8 Mbit/s, 3.6 Mbit/s, 7.2 Mbit/s and 14.4 Mbit/s in downlink.
Further speed grades are planned for the near future. The networks are then to be upgraded to HSPA Evolved, which provides speeds of 42Mbit downlink in its first release[1].
In addition to supporting high data speeds, HSDPA greatly increases the capacity of the network. Current HSDPA networks have the capacity to provide each customer with 30 gigabytes of data per month in addition to 1000 minutes of voice and 300 minutes of mobile TV[1].
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[edit] Adoption
As of March 19 2007, 100 HSDPA networks have commercially launched mobile broadband services in 54 countries. Near to 40 HSDPA networks support 3.6 Mbps peak data throughput (downlink direction). A growing number are delivering 7.2 Mbps peak data throughput, leveraging new higher-speed devices coming into the market. One network has been declared as “14.4 Mbps (peak) ready” while several additional networks will have this capability by end 2007. The first commercial HSUPA (uplink direction) network is launched, with several more set to follow in 2007.[2]
This protocol is a relatively simple upgrade where UMTS is already deployed.[1].
CDMA-EVDO networks had the early lead on performance, and Japanese and South Korean providers were the highly successful benchmark for that technology. Lately the situations seems to be changing in favour of HSDPA as an increasing number of providers worldwide are adopting it. South Korea's KTF and SK Telecom built nationwide HSDPA networks. KTF are selling HSDPA handsets to its customers on March 2007. SK Telecom announcing that by first half of 2007 it will be selling HSDPA handsets to its customers and that it will be cutting funding to its CDMA2000 network. A similar situation occurred in Australia, with Telstra announcing the closure of its CDMA-EVDO network and its replacement with a HSDPA network.
See also: List of Deployed HSDPA networks (not updated)
[edit] Technology
The HS-DSCH channel does away with two basic features of other W-CDMA channels—the variable spreading factor and fast power control—and instead uses
- Adaptive Modulation and Coding (AMC),
- fast packet scheduling at the Node B (Base Station), and
- fast retransmissions from Node B (known as HARQ-Hybrid Automatic Repeat Request)
to deliver the improved downlink performance. The concept of "incremental redundancy" is used in HARQ, where retransmissions contain different codings of the user data, relative to the original transmission. When a corrupted packet is received, the user device saves it, and combines it with subsequent retransmissions, to formulate an error-free packet as quickly and efficiently as possible. Even if the retransmitted packet(s) is itself corrupted, the combination of the sum of the errored transmissions can yield an error-free packet.
[edit] Fast Packet Scheduling
The HS-DSCH downlink channel is shared between users using channel-dependent scheduling to take advantage of favourable channel conditions to make best use of available radio conditions. Each user device periodically transmits (as often as 500 times per second) an indication of the downlink signal quality. The Node B uses this information received from all user devices to decide which users will be sent data on the next 2 ms frame and, for each user, how much data should be attempted. More data can be sent to users which report high downlink signal quality.
The amount of the channelisation code tree, and thus network bandwidth, allocated to HSDPA users is determined by the network. The allocation is "semi-static" in that it can be modified while the network is operating, but not on a frame-by-frame basis. This allocation represents a tradeoff between bandwidth allocated for HSDPA users, versus that for voice and non-HSDPA data users. The allocation is in units of channelisation codes for Spreading Factor 16, of which 16 exist, and of which up to 15 can be allocated to HSDPA.
When the Node B decides which users will receive data on the next 2 ms frame, it also determines which channelisation code(s) will be employed for each user, and this information is sent to the user devices over one or more HSDPA "scheduling channels" (these scheduling channels are not part of the HSDPA allocation previously mentioned, but are allocated separately). Thus, for a given 2 ms frame, data may be sent to a number of users simultaneously, using different channelisation code. The maximum number of users to receive data on a given 2 ms frame is determined by the number of allocated channelisation codes. This differs from CDMA2000 1xEV-DO, where data is sent to only one user at a time.
[edit] Adaptive Modulation and Coding
The modulation scheme and coding is changed on a per-user basis depending on signal quality and cell usage.
QPSK is the initial modulation scheme, however, in good radio conditions the introduction of 16QAM modulation will improve data throughput rates by approximately double that of QPSK. QPSK with 5 Code allocation will typically offer up to 1.8 Mbit/s peak data rates. 16QAM with 5 Codes will increase this to 3.6 Mbit/s. Additional Codes (e.g. 10, 15) can also be used to improve these data rates or extend the network capacity throughput significantly. Theoretically, HSDPA can give throughput up to 10.8 Mbit/s.
[edit] Other Improvements
HSDPA is part of the UMTS standards from release 5 onwards, which also accompanies an improvement on the uplink providing a new bearer of 384 kbit/s (previous max bearer was 128 kbit/s).
As well as improved data rates that are associated with HSDPA one of the key benefits that are seen is the reduction on latency, improving the round trip time for applications.
Along with the HS-DSCH channel, three new physical channels are also introduced. One is the High Speed-Shared Control CHannel (HS-SCCH) which informs the user that data will be sent on the HS-DSCH 2 slots ahead. The second one is the Uplink High Speed-Dedicated Physical Control CHannel (HS-DPCCH), which carries acknowledgment information and current channel quality indicator (CQI) of the user. This value is then used by the Node-B in calculating how much data to send to the UE on the next transmission. The third downlink physical channel is the HS-PDSCH (High Speed-Physical Downlink Shared CHannel). This is the physical channel mapped to the above HS-DSCH transport channel that carries actual user data.
[edit] HSDPA UE categories
HSDPA comprises various versions with different data speeds.[3]
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Category Max. number of
HS-DSCH codesModulation Max. data rate
[Mbit/s]1 5 QPSK and 16-QAM 1.2 2 5 QPSK and 16-QAM 1.2 3 5 QPSK and 16-QAM 1.8 4 5 QPSK and 16-QAM 1.8 5 5 QPSK and 16-QAM 3.6 6 5 QPSK and 16-QAM 3.6 7 10 QPSK and 16-QAM 7.3 8 10 QPSK and 16-QAM 7.3 9 15 QPSK and 16-QAM 10.2 10 15 QPSK and 16-QAM 14.4 11 5 QPSK only 0.9 12 5 QPSK only 1.8
[edit] Roadmap
The first phase of HSDPA has been specified in 3GPP release 5. Phase one introduces new basic functions and is aimed to achieve peak data rates of 14.4 Mbps (see above). Newly introduced are the High Speed Downlink Shared Channels (HS-DSCH), the adaptive modulation QPSK and 16QAM and the High Speed Medium Access protocol (MAC-hs) in the Node-B.
The second phase of HSDPA is specified in the upcoming 3GPP release 7 and has been named HSPA Evolved. It can achieve data rates of up to 42 Mbps[1]. It will introduce antenna array technologies such as beamforming and Multiple Input Multiple Output (MIMO). Beam forming can be described as focusing the transmitted power of an antenna in a beam towards the user’s direction. MIMO uses multiple antennas at the sending and receiving side. Deployments are scheduled to begin in the second half of 2008.
After HSDPA the roadmap leads to HSOPA, a technology under development for specification in 3GPP Release 8. This project is called the LTE (Long Term Evolution) initiative. It aims to achieve data rates of up 200 Mbps for downlink and 100 Mpbs for uplink using OFDMA modulation.
For more detailed info, refer to [1].
[edit] Handsets
A total of 171 devices from 47 suppliers have been launched to date, comprising: 53 Handsets, 35 Notebooks, 30 Datacards, 19 Wireless Routers, 15 Modems, 11 Embedded Module, 2 Wireless Modules, 1 Wireless Residental Gateway, 1 Media Player, 1 Camera, 1 GPS Handset, 1 Convergence Platform & 1 Baseband Processor. For more detailed info, please refer to www.gsmworld.com/HSPA
- Sony Ericsson released the Z750, a HSDPA Quad-EDGE enabled phone in the first quarter of 2007.
- Palm, Inc. has released the Treo 750, which does UMTS today and HSDPA via a firmware upgrade in 2007 for Cingular.
- Nokia have announced that they will release their first HSDPA device, the N95, in the first quarter of 2007 [4][5]. This is a category 6 device meaning up to 3.6 Mbit downlink speeds. They also have E90 and 6110 Navigator to be released with HSDPA.
- Vodafone New Zealand recently released its HSDPA mobile broadband device the Vodem. This device is designed for use with notebook or desktop computers and is in fact a rebadged Huawei Technologies E220 USB Modem.
- LG currently offer a number of HSDPA handsets in Australia, such as the TU500 and U830. They also offer the CU500 with Cingular in the United States.
- ZTE has released their first device in Australia, rebadged the Telstra 850.
- Motorola has announced 2 HSDPA handsets called the RAZR MAXX and RAZR XX (also known as RAZR V3xx), which are scheduled for release in Q4 2006 [6].
- Samsung has 3 new HSDPA handsets released in the United States by Cingular. The A707 flip-phone and the Blackjack PDA Smartphone (both released November 16, 2006), and the SGH-ZX20. Samsung also has 2 HSDPA handsets available in Australia, the A501 and the A701, the Z560 in the Philippines, and 1 slider in the U.K., the Z720. The new i607 BlackJack also supports HSDPA.
- BenQ has released its first HSDPA mobile phone, the EF91, in July 2006. Since BenQ-Siemens mobile has filed for bankruptcy Q3/2006, the future of BenQ mobile phones is unclear.
- HTC has released the TYTN handset/smartphone (branded as the MDA Vario II on T-Mobile, Qtek 1605 on Vodafone, the SPV M3100 on Orange, the Dopod 838Pro and the Dopod D810 on 3 (Hutchinson) Australia, the I-Mate JasJam on Cellcom and the Cingular 8525 on Cingular) which supports HSDPA.
- NEC released the N902iX High Speed along with NTT Docomo's HSDPA network launch on Aug 31 2006. It is the first handset capable of 3.6Mbps to go into commercial service.
[edit] HSDPA in notebooks
- Fujitsu Siemens Computers was the 1st Notebook supplier that integrated a UMTS Module in several Notebooks. LIFEBOOK Q2010 supports not only Data, you are also able to use this Notebook as Telephone. The following Notebooks from Fujitsu Siemens can be ordered with UMTS: LIFEBOOK P1610, T4215, E8210, AMILO Pro 3525, 3545 and AMILO Si 1848.
- Acer integrate an HSDPA module in some laptops.
- Dell began releasing, in June 2006, laptops with in-built HSDPA chips from Vodafone, enabling the laptops to be continuously connected to the internet via Vodafone's 3.5G network in the UK and several other countries. The Dell laptop models currently with this capability are the Latitude D420, D620, D820, and XPS M1210 models (see [7]). As mentioned above, the D620, D820, and XPS M1210 models are also sold in the United States with HSDPA service from Cingular Wireless.
- HTC have announced an HSDPA device running Windows Mobile 5.0 on 7 Sep 2006, which will ship as the P3600.
- HP UK has announced that they will begin integrating Vodafone's 3.5G HSDPA technology into their laptops [8]
- Intel was to integrate HSDPA wireless technology (supplied by Nokia) into their next generation of Centrino chipset for laptops known as Santa Rosa, but this was scrapped when both Nokia and Intel decided there was not enough of a business case[9]. The new chipset was due to be available in laptops world wide in the first half of 2007[10] and would have therefore eliminated the need for laptop owners buying separate HSDPA cards as the technology would have already been integrated in the laptop.
- Lenovo has been shipping Vodafone's high speed HSDPA mobile data connectivity technology in various models of their Lenovo and IBM branded ThinkPad notebooks since mid-2006.[11]
- Panasonic supports EDGE and embedded HSDPA integrated inside several of their Toughbook models.
- Option sells HSDPA enabled PCMCIA data cards. It also offers embedded wireless modules to laptop manufacturers.
- Flybook [12] released their V33i model with HSDPA in October 2006.
[edit] See also
- 3GPP
- 3GPP Long Term Evolution
- Cellular router
- High-Speed Uplink Packet Access
- High-Speed OFDM Packet Access
- Mobile Internet access worldwide
- Quad band
- Triband (telephone)
- UMTS
[edit] References
- ^ a b c d e How to realise the benefits of mobile broadband today GSMA publication. 2007
- ^ HSDPA and beyond
- ^ Nokia's N95 smartphone goes legit
- ^ It's what computers have become - the new Nokia N95 September 26, 2006
- ^ Motorola unveils slimmer, 'super 3G' RAZRs
- ^ Dell (UK)
- ^ zdnet news
- ^ Forbes
- ^ news.com
- ^ ThinkPad notebooks IBM
- ^ Flybook
[edit] Literature
- Martin Sauter: Communication Systems for the Mobile Information Society, John Wiley, September 2006, ISBN 0-470-02676-6
[edit] External links
- HSDPA and beyond
- Understand HSDPA's implementation challenges
- HSDPA Technical Description
- HSDPA Fact Sheet and Deployment List
- Qualcomm: HSDPA for Improved Downlink Data Transfer White Paper
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| Wired: | Dial-up, ISDN, DSL, Cable, Fiber Optic, Power-line internet |
| Wireless: | Wi-Fi, WiBro, WiMAX, UMTS-TDD, HSDPA, Satellite |
