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High-Speed Packet Access (HSPA) |
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High-Speed Packet Access (HSPA) High Speed Packet Access (HSPA)[1] is a collection of two mobile telephony protocols, High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA), that extends and improves the performance of existing WCDMA protocols. A further standard, Evolved HSPA (also known as HSPA+), is soon to be released. OverviewHSDPA and HSUPA provide increased performance by using improved modulation schemes and by refining the protocols by which handsets and base stations communicate. These improvements lead to a better utilization of the existing radio bandwidth provided by WCDMA. HSPA improves the end-user experience by increasing peak data rates up to 14 Mbit/s in the downlink and 5.8 Mbit/s in the uplink. It also reduces latency and provides up to five times more system capacity in the downlink and up to twice as much system capacity in the uplink, reducing the production cost per bit compared to original WCDMA protocols. HSPA increases peak data rates and capacity in several ways: - Shared-channel transmission, which results in efficient use of available code and power resources in WCDMA
- A shorter Transmission Time Interval (TTI), which reduces round-trip time and improves the tracking of fast channel variations
- Link adaptation, which maximizes channel usage and enables the base station to operate close to maximum cell power
- Fast scheduling, which prioritizes users with the most favorable channel conditions
- Fast retransmission and soft-combining, which further increase capacity
- 16QAM (Quadrature Amplitude Modulation), which yields higher bit-rates
HSPA has been commercially deployed by over 200 operators in more than 80 countries. Many HSPA rollouts can be achieved by a software upgrade to existing 3G networks, giving HSPA a headstart over WiMax, which requires dedicated network infrastructure. Rich variety of HSPA enabled terminals, more than 1000 available today together with ease of use gives rising sales of HSPA-enabled mobiles and are helping to drive the HSPA. High Speed Downlink Packet Access (HSDPA)The first step required to upgrade WCDMA to HSPA is to improve the downlink by introducing HSDPA. The improved downlink provides up to 14 Mbit/s with significantly reduced latency. The channel reduces the cost per bit and enhances support for high-performance packet data applications. HSDPA is based on shared channel transmission and its key features are shared channel and multi-code transmission, higher-order modulation, short Transmission Time Interval (TTI), fast link adaptation and scheduling along with fast hybrid Automatic Repeat reQuest (ARQ). The upgrade to HSDPA is often just a software update for most WCDMA networks, and as of May 2008 90 percent of WCDMA networks are upgraded to HSDPA.[2] With HSDPA mobile broadband becomes a reality and users can download files, read mails and browse web pages with the same end-user experience as that of fixed broadband. Majority of deployments provide up to 7.2 Mbit/s in the down-link and 14 Mbit/s is already available as soon as the devices are available in the market. Voice calls are usually prioritized over data transfer. Singapore's three network providers M1, StarHub and SingTel provide up to 28 Mbit/s throughout the entire island. The Australian provider Telstra provides up to 14.4 Mbit/s nationwide, as does the Swiss provider Swisscom. The Croatian VIPnet network supports the speed of 7.2 Mbit/s in down-link, as does Rogers Wireless in Canada. Rogers Wireless now supports 21 Mbit/s in the Toronto area.[3] In South Korea, a nationwide 7.2 Mbit/s coverage is now established by SK Telecom and KTF. In Hong Kong PCCW and Smartone-Vodafone also provide 7.2 Mbit/s coverage. In Portugal all the mobile phone operators support 14 Mbit/s HSDPA, and the Sri-Lankan companies Airtel Pvt Ltd and Mobitel Pvt Ltd also provide 7.2 Mbit/s in the Asian region. High Speed Uplink Packet Access (HSUPA)The second major step in the WCDMA upgrade process is to upgrade the uplink, which is introduced in 3GPP Release 6. Upgrading to HSUPA is often only a software update. Enhanced Uplink adds a new transport channel to WCDMA, called Enhanced Dedicated Channel (E-DCH). An enhanced uplink creates opportunities for a number of new applications including VoIP, uploading pictures and sending large e-mails. The enhanced uplink increases the data rate (up to 5.8 Mbit/s), and the capacity, and also reduces latency. The enhanced uplink features several improvements similar to those of HSDPA, such as multi code transmission, short Transmission Time Interval (TTI), fast scheduling and fast hybrid Automatic Repeat reQuest (ARQ). In Singapore, Starhub announced a 1.9 Mbit/s HSUPA Service as part of its new MaxMobile plan in 1 August 2007.[4] In Finland, Elisa announced on 30 August 2007 1.4 Mbit/s HSUPA to most large cities with plans to add the service to its whole 3G network within months.[5] 3 Italia and Ericsson announced on 16 July 2008 the successful tests of HSUPA 5.8 Mbit/s in the live network of 3 Italia.[6] Evolved High Speed Packet Access (HSPA+)Evolved HSPA (also known as: HSPA Evolution, HSPA+, I-HSPA or Internet HSPA) is an upcoming wireless broadband standard defined in 3GPP release 7 and 8 of the WCDMA specification. Evolved HSPA provides data rates up to 42 Mbit/s in the downlink and 11 Mbit/s in the uplink (per 5 MHz carrier) with multiple input, multiple output (MIMO) technologies and higher order modulation. Dual-Cell HSDPA (DC-HSDPA)Dual-Cell HSDPA, part of 3GPP Release 8, is the natural evolution of HSPA by means of carrier aggregation.[7] An HSPA+ network can theoretically support up to 28Mbit/s and 42Mbit/s with a single 5 MHz carrier for Rel7 (MIMO) and Rel8 (Higher Order Modulation + MIMO), in good channel condition with low correlation between transmit antennas. Alternatively DC-HSPA can be used from Release 8 where the MAC scheduler can allocate two HSPA carrier in parallel and double the bandwidth from 5 MHz to 10 MHz. Besides the throughput gain from double the bandwidth, some diversity and joint scheduling gains can also be expected.[8] This can particularly improve the QoS for end users in poor environment conditions that can not gain from MIMO and Higher Modulation only. From Release 9 onwards it will be possible to use DC-HSDPA in combination with MIMO used on both carrier. The support of MIMO in combination with DC-HSDPA will allow operators deploying Release 7 MIMO to benefit from the DC-HSDPA functionality as defined in Release 8. Dual-Cell HSUPA (DC-HSUPA)Similar enhancements as introduced with DC-HSDPA in the downlink for UMTS Release 8 are being standardized for UMTS Release 9 in the uplink called Dual-Cell HSUPA.[9] DC-HSUPA will have similar limitations, for instance that the carriers have to belong to the same Node-B and have to be adjacent. Furthermore, it is assumed that at least 2 carriers are configured simultaneously in the downlink and have the same duplex distance to the uplink. The dual carrier transmission will only be applied to HSUPA UL physical channels and DPCCH. The standardisation of Release 9 is expected to be completed in December 2009. Multi-carrier HSPA (MC-HSPA)While the aggregation of more than two carriers has been studied the 3GPP specification does not yet allow this option. Nevertheless it seems likely that such option will be added at a later state of the technology. See also References- ^ Nomor Research: White Paper "Technology of High Speed Packet Access", nomor.de
- ^ "GSM/3G Market Update". Global mobile Suppliers Association. June 2, 2008. http://www.gsacom.com/news/gsa_247.php4. Retrieved February 1, 2010.
- ^ Rogers.com
- ^ Starhub.com
- ^ Elisa.fr
- ^ Ericsson.com
- ^ Nomor Research White Paper: Dual-cell HSPA and its Evolution, nomor.de
- ^ R1-081546, “Initial multi-carrier HSPA performance evaluation”, Ericsson, 3GPP TSG-RAN WG1 #52bis, April, 2008
- ^ Nomor 3GPP Newsletter 2009-03: Standardisation updates on HSPA Evolution, nomor.de
Literature- Martin Sauter: Communication Systems for the Mobile Information Society, John Wiley, September 2006, ISBN 0-470-02676-6
External links- GSMworld.com, Official HSPA website
- Linkedin.com, Public HSPA Discussion Forum
- HuaweiE220.com, 7.2 Mbps Highspeed USB-Modem
- Nomor Research: White Paper "Technology of High Speed Packet Access", nomor.de
- 3.5G driving rapid mobile broadband growth, news.com
- Nomor Research: White Paper "Dual-Cell HSDPA and its Evolution, nomor.de
- Basic concepts of HSPA (Ericsson White Paper), ericsson.com
- HSPA, the Undisputed Choice for Mobile Broadband (Ericsson White Paper), ericsson.com
- Nomor 3GPP Newsletter 2009-03: Standardisation updates on HSPA Evolution, nomor.de
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(2.5G, 2.75G) | | | | 3G (IMT-2000) | | | 3G transitional
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High-Speed Downlink Packet Access (HSDPA) is an enhanced 3G (third generation) mobile telephony communications protocol in the High-Speed Packet Access (HSPA) family, also coined 3.5G, 3G+ or turbo 3G, which allows networks based on Universal Mobile Telecommunications System (UMTS) to have higher data transfer speeds and capacity. Current HSDPA deployments support down-link speeds of 1.8, 3.6, 7.2 and 14.0 Mbit/s. Further speed increases are available with HSPA+, which provides speeds of up to 42 Mbit/s downlink and 84 Mbit/s with Release 9 of the 3GPP standards.[1].
Technology
HS-DSCH channel
For HSDPA, a new transport layer channel, High-Speed Downlink Shared Channel (HS-DSCH), has been added to W-CDMA specification. It is implemented by introducing three new physical layer channels: HS-SCCH, HS-DPCCH and HS-PDSCH. The High Speed-Shared Control Channel (HS-SCCH) informs the user that data will be sent on the HS-DSCH 2 slots ahead. The Uplink High Speed-Dedicated Physical Control Channel (HS-DPCCH) carries acknowledgment information and current channel quality indicator (CQI) of the user. This value is then used by the base station to calculate how much data to send to the user devices on the next transmission. The High Speed-Physical Downlink Shared Channel (HS-PDSCH) is the channel mapped to the above HS-DSCH transport channel that carries actual user data.
Hybrid automatic repeat-request (HARQ)
Data is transmitted together with error correction bits. Minor errors can thus be corrected without retransmission.
If retransmission is needed, the user device saves the packet and later combines it with retransmitted packet to recover the error-free packet as efficiently as possible. Even if the retransmitted packets are corrupted, their combination can yield an error-free packet. Retransmitted packet may be either identical (Chase combining) or different from the first transmission (incremental redundancy).
The round-trip time for retransmissions is improved since the retransmissions are done from base station instead of radio network controller.
Fast packet scheduling
The HS-DSCH downlink channel is shared between users using channel-dependent scheduling to make the best use of available radio conditions. Each user device continually transmits an indication of the downlink signal quality, as often as 500 times per second. Using this information from all devices, the base station decides which users will be sent data on the next 2 ms frame and how much data should be sent for each user. 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 trade-off 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 up to 15 can be allocated to HSDPA. When the base station decides which users will receive data on the next frame, it also decides which channelisation codes will be used for each user. This information is sent to the user devices over one or more "scheduling channels"; these 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 codes. The maximum number of users to receive data on a given 2 ms frame is determined by the number of allocated channelisation codes. By contrast, in CDMA2000 1xEV-DO, data is sent to only one user at a time.
Adaptive modulation and coding
The modulation scheme and coding is changed on a per-user basis depending on signal quality and cell usage. The initial scheme is Quadrature phase-shift keying (QPSK), but in good radio conditions 16QAM and 64QAM can significantly increase data throughput rates. With 5 Code allocation, QPSK typically offers up to 1.8 Mbit/s peak data rates, while 16QAM offers up to 3.6. Additional codes (e.g. 10, 15) can also be used to improve these data rates or extend the network capacity throughput significantly.
Other improvements
HSDPA is part of the UMTS standards since release 5, which also accompanies an improvement on the uplink providing a new bearer of 384 kbit/s. The previous maximum bearer was 128 kbit/s.
As well as improving data rates, HSDPA also decreases latency and so the round trip time for applications.
In later 3GPP specification releases HSPA+ increases data rates further by adding 64QAM modulation, MIMO and Dual-Cell HSDPA operation, i.e. two 5 MHz carriers are used simultaneously.
HSDPA User Equipment (UE) categories
HSDPA comprises various versions with different data speeds. The following table is derived from table 5.1a of the release 9 version of 3GPP TS 25.306 [2] and shows maximum speeds of different device classes and by what combination of features they are achieved. In 2009 the most common devices are category 6 (3.6 MBit/s) and category 8 (7.2 MBit/s) with retail prices around 60 euros without subscription.
| Category | Max. number of
HS-DSCH codes | Modulation | MIMO - Dual Carrier | code rate required to
achieve max. data rate[3] | Max. data rate
[Mbit/s] |
|---|
| 1 | 5 | QPSK and 16-QAM | | .76 | 1.2 |
| 2 | 5 | QPSK and 16-QAM | | .76 | 1.2 |
| 3 | 5 | QPSK and 16-QAM | | .76 | 1.8 |
| 4 | 5 | QPSK and 16-QAM | | .76 | 1.8 |
| 5 | 5 | QPSK and 16-QAM | | .76 | 3.6 |
| 6 | 5 | QPSK and 16-QAM | | .76 | 3.6 |
| 7 | 10 | QPSK and 16-QAM | | .75 | 7.2 |
| 8 | 10 | QPSK and 16-QAM | | .76 | 7.2 |
| 9 | 15 | QPSK and 16-QAM | | .70 | 10.1 |
| 10 | 15 | QPSK and 16-QAM | | .97 | 14.0 |
| 11 | 5 | QPSK only | | .76 | 0.9 |
| 12 | 5 | QPSK only | | .76 | 1.8 |
| 13 | 15 | QPSK, 16-QAM and 64-QAM | | .82 | 17.6 |
| 14 | 15 | QPSK, 16-QAM and 64-QAM | | .98 | 21.1 |
| 15 | 15 | QPSK, 16-QAM | MIMO | .81 | 23.4 |
| 16 | 15 | QPSK, 16-QAM | MIMO | .97 | 28.0 |
| 19 | 15 | QPSK, 16-QAM, 64-QAM | MIMO | .82 | 35.3 |
| 20 | 15 | QPSK, 16-QAM, 64-QAM | MIMO | .98 | 42.2 |
| 21 | 15 | QPSK, 16-QAM | Dual-Cell HSDPA | .81 | 23.4 |
| 22 | 15 | QPSK, 16-QAM | Dual-Cell HSDPA | .97 | 28.0 |
| 23 | 15 | QPSK, 16-QAM, 64-QAM | Dual-Cell HSDPA | .82 | 35.3 |
| 24 | 15 | QPSK, 16-QAM, 64-QAM | Dual-Cell HSDPA | .98 | 42.2 |
| 25 | 15 | QPSK, 16-QAM | Dual-Cell HSDPA + MIMO | .81 | 46.7 |
| 26 | 15 | QPSK, 16-QAM | Dual-Cell HSDPA + MIMO | .97 | 55.9 |
| 27 | 15 | QPSK, 16-QAM, 64-QAM | Dual-Cell HSDPA + MIMO | .82 | 70.6 |
| 28 | 15 | QPSK, 16-QAM, 64-QAM | Dual-Cell HSDPA + MIMO | .98 | 84.4 |
The max data rates given on the table are physical layer data rates. Application layer data rate is approximately 85% of that, due to the inclusion of IP headers etc.
Roadmap
The first phase of HSDPA has been specified in the 3rd Generation Partnership Project (3GPP) release 5. Phase one introduces new basic functions and is aimed to achieve peak data rates of 14.0 Mbit/s (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 base station.
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 Mbit/s.[1] It introduces antenna array technologies such as beamforming and Multiple-input multiple-output communications (MIMO). Beam forming focuses 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.
Further releases of the standard have introduced dual carrier operation, i.e. the simultaneous use of two 5 MHz carrier. By combining this with MIMO transmission, peak data rates of 84 Mbit/s can be reached under ideal signal conditions.
After HSPA Evolved, the roadmap leads to E-UTRA (Previously "HSOPA"), the technology specified in 3GPP Release 8. This project is called the Long Term Evolution initiative. The first release of LTE offers data rates of over 320 Mbit/s for downlink and over 170 Mbit/s for uplink using OFDMA modulation.[1]
Adoption
As of August 28, 2009, 250 HSDPA networks have commercially launched mobile broadband services in 109 countries. 169 HSDPA networks support 3.6 Mbit/s peak downlink data throughput. A growing number are delivering 21 Mbit/s peak data downlink and one network has been upgraded to 28 Mbit/s. Several others will have this capability by end 2009 and the first network supporting 42 Mbit/s network is set to come online in late 2009.
This protocol is a relatively simple upgrade where UMTS is already deployed.[1]
CDMA-EVDO networks had the early lead on performance, and Japanese providers were highly successful benchmarks for it. But lately this seems to be changing in favour of HSDPA as an increasing number of providers worldwide are adopting it. In Australia, Telstra announced that its CDMA-EVDO network would be replaced with a HSDPA network (since named NextG), offering high speed internet, mobile television and traditional telephony and video calling. Rogers Wireless deployed HSDPA system 850/1900 in Canada on April 1, 2007. In July 2008, Bell Canada and Telus announced a joint plan to expand their current shared EVDO/CDMA network to include HSDPA.[4] Bell Canada launched their joint network November 4, 2009, while Telus launched November 5, 2009.[5] In January 2010, T-Mobile USA adopted HSDPA. [6]
Marketing as mobile broadband
During 2007, an increasing number of telcos worldwide began selling HSDPA USB modems as mobile broadband connections. In addition, the popularity of HSDPA landline replacement boxes grew—providing HSDPA for data via Ethernet and WiFi, and ports for connecting traditional landline telephones. Some are marketed with connection speeds of "up to 7.2 Mbit/s",[7] which is only attained under ideal conditions. As a result these services can be slower than expected, especially when in fringe coverage indoors. However, signal strength can be greatly improved by using commercial solutions that can attach 3G external antennas.[8]
See also
References
Further reading
- Sauter, Martin (2006). Communication Systems for the Mobile Information Society. Chichester: John Wiley. ISBN 0470026766.
External links
3G Information 
