hsdpa

High-Speed Downlink Packet Access From Wikipedia, the free encyclopedia

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High-Speed Downlink Packet Access (HSDPA) is an enhanced 3G (third-generation) mobile-

telephony communications protocol in theHigh-Speed Packet Access (HSPA) family, also dubbed 3.5G, 3G+ or

turbo 3G, which allows networks based on Universal Mobile Telecommunications System (UMTS) to have

higher data-transfer speeds and capacity. As of 2013 HSDPA deployments can support down-link speeds of up

to 42.3 Mbit/s. HSPA+ offers further speed increases, providing speeds of up to 337.5 Mbit/s with Release 11

of the 3GPP standards.[1]

Contents

[hide]

1 Technology

o 1.1 High-Speed Downlink Shared Channel

o 1.2 Hybrid automatic repeat-request (HARQ)

o 1.3 Fast packet scheduling

o 1.4 Adaptive modulation and coding

o 1.5 Dual-Cell

o 1.6 Other improvements

2 User Equipment (UE) categories

3 Roadmap

4 Adoption

o 4.1 Marketing as mobile broadband

5 See also

6 References

7 Further reading

8 External links

Technology[edit]

High-Speed Downlink Shared Channel[edit]

For HSDPA, a new transport layer channel, High-Speed Downlink Shared Channel (HS-DSCH), has been

added to UMTS release 5 and further 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 to which the above HS-DSCH transport channel is mapped that carries actual user data.

Hybrid automatic repeat-request (HARQ)[edit]

Data is transmitted together with error correction bits. Minor errors can thus be corrected without

retransmission; see forward error correction.

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).

Since HARQ retransmissions are processed at the physical layer, their 12 ms round-trip time is much lower

compared to higher layer retransmissions.

Fast packet scheduling[edit]

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 in 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 the HS-

DSCH. When the base station decides which users will receive data in the next frame, it also decides which

channelisation codes will be used for each user. This information is sent to the user on one of up to 4 HS-

SCCHs, which are not part of the HS-DSCH 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.

Adaptive modulation and coding[edit]

The modulation scheme and coding are changed on a per-user basis, depending on signal quality and cell

usage. The initial scheme isquadrature 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 Mbit/s. Additional codes (e.g. 10, 15) can also be

used to improve these data rates or extend the network capacity throughput significantly.

Dual-Cell[edit]

Dual Cell (DC-)HSDPA, known also as Dual Carrier, is the natural evolution of HSPA by means of carrier

aggregation in the downlink.[2]

UMTS licenses are often issued as 10 or 15 MHz paired spectrum allocations.

The basic idea of the multicarrier feature is to achieve better resource utilization and spectrum efficiency by

means of joint resource allocation and load balancing across the downlink carriers.

An advanced HSPA network can theoretically support up to 28 Mbit/s and 42.2 Mbit/s with a single 5 MHz

carrier for Rel7 (MIMO with 16QAM) and Rel8 (64-QAM + MIMO), in good channel conditions with low

correlation between transmit antennas. An alternative method to double the data rates is to double the

bandwidth to 10 MHz (i.e. 25 MHz) by using DC-HSDPA. Additionally, some diversity and joint scheduling

gains can also be expected[3]

with improved QoS for end users in poor environment conditions where existing

techniques such as MIMO spatial multiplexing cannot be used to increase data rates. In 3GPP a study item

was completed in June 2008. The outcome can be found in technical report 25.825.[4]

New HSDPA User

Equipment categories 21-24 have been introduced that support DC-HSDPA. DC-HSDPA can support up to

42.2 Mbit/s, but unlike HSPA, it does not need to rely on MIMO transmission.

From Release 9 onwards it will be possible to use DC-HSDPA in combination with MIMO used on both

carriers.[5]

This will allow theoretical speed of up to 84.4 Mbit/s.

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. While in Release 8 DC-HSDPA can only operate on

adjacent carriers, Release 9 also allows that the paired cells can operate on two different frequency bands.

Future releases will allow the use of up to four carriers simultaneously.

Other improvements[edit]

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 HSDPAoperation, i.e. two 5 MHz carriers are used simultaneously.

User Equipment (UE) categories[edit]

HSDPA comprises various versions with different data speeds.

The following table is derived from table 5.1a of the release 11 of 3GPP TS 25.306[6]

and shows maximum data

rates of different device classes and by what combination of features they are achieved. The per-cell per-

stream data rate is limited by the Maximum number of bits of an HS-DSCH transport block received within an

HS-DSCH TTI and the Minimum inter-TTI interval. The TTI is 2 ms. So for example Cat 10 can decode 27952

bits/2 ms = 13.976 MBit/s (and not 14.4 MBit/s as often claimed incorrectly). Categories 1-4 and 11 have inter-

TTI intervals of 2 or 3, which reduces the maximum data rate by that factor. Dual-Cell and MIMO 2x2 each

multiply the maximum data rate by 2, because multiple independent transport blocks are transmitted over

different carriers or spatial streams, respectively. The data rates given in the table are rounded to one decimal

point.

3GPP

Release Category

Max. number

of

HS-DSCH

codes

Modulation[note

1]

MIMO, Multi-Cell

Code rate at

max. data

rate[note 2]

Max. data

rate

[Mbit/s][note 3]

Release 5 1 5 16-QAM

.76 1.2


.76 1.2


.76 1.8


.76 1.8


.76 3.6


.76 3.6


.75 7.2


.76 7.2


.70 10.1


.97 14.0

Release 5 11 5 QPSK

.76 0.9

Release 5 12 5 QPSK

.76 1.8


.82 17.6


.98 21.1

Release 7 15 15 16-QAM MIMO 2x2 .81 23.4

Release 7 16 15 16-QAM MIMO 2x2 .97 28.0

Release 7 17

15 64-QAM

.82 17.6

15 16-QAM MIMO 2x2 .81 23.4

Release 7 18

15 64-QAM

.98 21.1

15 16-QAM MIMO 2x2 .97 28.0

Release 8 [note 4]

19 15 64-QAM MIMO 2x2 .82 35.3

Release 8

[note 5] 20 15 64-QAM MIMO 2x2 .98 42.2

Release 8 21 15 16-QAM Dual-Cell .81 23.4




Release 9 25 15 16-QAM Dual-Cell + MIMO

2x2 .81 46.7


2x2 .97 55.9


2x2 .82 70.6


2x2 .98 84.4

Release 10 29 15 64-QAM Triple-Cell .98 63.3

Release 10 30 15 64-QAM Triple-Cell + MIMO

2x2 .98 126.6

Release 10 31 15 64-QAM Quad-Cell .98 84.4

Release 10 32 15 64-QAM Quad-Cell + MIMO

2x2 .98 168.8

Release 11 33 15 64-QAM Hexa-Cell .98 126.6

Release 11 34 15 64-QAM Hexa-Cell + MIMO

2x2 .98 253.2

Release 11 35 15 64-QAM Octa-Cell .98 168.8

Release 11 36 15 64-QAM Octa-Cell + MIMO

2x2 .98 337.5


4x4 .98 168.8

Release 11 38 15 64-QAM Quad-Cell + MIMO

4x4 .98 337.5

Notes:

1. Jump up^ 16-QAM implies QPSK support, 64-QAM implies 16-QAM and QPSK support.

2. Jump up^ The maximal code rate is not limited. A value close to 1 in this column indicates that the

maximum data rate can be achieved only in ideal conditions. The device is therefore connected directly

to the transmitter to demonstrate these data rates.

3. Jump up^ The maximum data rates given in the table are physical layer data rates. Application layer

data rate is approximately 85% of that, due to the inclusion of IP headers (overhead information) etc.

4. Jump up^ Category 19 was specified in Release 7 as "For further use". Not until Release 8

simultaneous use of 64QAM and MIMO were allowed to obtain the specified max. data rate.

5. Jump up^ Category 20 was specified in Release 7 as "For further use". Not until Release 8

simultaneous use of 64QAM and MIMO were allowed to obtain the specified max. data rate.

Roadmap[edit]

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 3GPP release 7 and has been named HSPA Evolved. It

can achieve data rates of up to 42.2 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 users direction. MIMO uses multiple antennas at

the sending and receiving side. Deployments were 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 84.4 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 Releases 8 and 10. This project is called the Long Term Evolution initiative. Different LTE user

equipment categories offer data rates up to 3 Gbit/s for downlink and 1.5 Gbit/s for uplink

using OFDMA modulation.

Adoption[edit]

As of 28 August 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 28 Mbit/s. Several others will have this capability by end

2009 and the first 42 Mbit/s network came online in Australia in February 2010. Telstra switches on

42 Mbit/s Next G, plans 84 Mbit/s through the implementation of HSPA+ Dual Carrier plus MIMO

technology upgrade in 2011.[7]

This protocol is a relatively simple upgrade where UMTS is already

deployed.[1]

First week in May 2010, Second-ranked Indonesian cellular operator Indosat launched the first

DC-HSPA+ 42 Mbit/s network, beating Australia's Telstra, Singapore's StarHub and Hong Kong's CSL to

stake its claim as the first operator in Asia-Pacific to offer theoretical download speeds of 42 Mbit/s via

HSPA+.[8][9]

CDMA2000-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, Telstraannounced 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.[10]

Bell Canada launched their joint

network November 4, 2009, while Telus launched November 5, 2009.[11]

In January 2010, T-Mobile USA

adopted HSDPA.[12]

Telstra in Australia announced they had implemented Dual-Cell HSDPA in their live NextG network on 18

January 2010. On 15 February 2010 they announced that the upgrade had been completed to section of

their network in capital cities and major regional centers. As of July 2010, two devices were available; a

USB device manufactured by Sierra Wireless, the AirCard 312U, and a portable WiFi hot spot device.

In October 2010, Vodafone in Portugal announced[13]

a commercial offer of 43.2 Mbit/s download and

11.4 Mbit/s upload. The service is currently available in Lisbon.

On Nov 18 2010, Bell Canada announced it would begin doubling its network speeds to 42 Mbit/s

beginning Nov 23 2010 using HSPA+ Dual Cell technology.[14]

On December 3, 2010, E Mobile in Japan announced the availability of 42 Mbit/s service based upon DC-

HSDPA.[15]

On March 10, 2011, SaskTel announced that Dual-Cell HSPA+ will be available in Saskatoon and Regina

by the summer.[16]

SaskTel also announced that the first device to take advantage of this new technology

will be the Novatel Wireless MC547 Mobile Internet Stick.

On August 23, 2011, Telenor Hungary started Dual-Cell HSPA+ service in Budapest and its

surroundings.[17]

In 2011, Viva Telecom Kuwait started offering Dual-Cell HSPA+ to its customers.[18]

In 2011, Personal; a Telecom Argentina / Telecom Italia subsidiary in Paraguay, started offering Dual-Cell

HSPA+ to its customers.[19]

Also in 2011 two carriers in Finland, Elisa and DNA started offering "4G" backed up by Dual-Cell HSPA+

whereas LTE coverage is merely spotty in nature.[20][21]

In February 2012, Personal from Paraguay started offering Dual-Carrier HSPA+ to its customers.[22]

In February 2012, Three UK announced the start of its trials of DC-HSDPA. Full rollout will begin in

Summer 2012. As of November 2012 50 cities have been chosen for the initial roll out to be completed by

the end of 2012 - with Belfast joining in January 2013. They plan to cover 50% of the UK population by the

end of 2012.[23]

By mid 2012, 3 in Italy had deployed DC-HSDPA 42Mbit/s all over its network.

In August 2012, Etisalat Sri Lanka announced the start of its DC-HSPA+ network. First operator in a

South Asian country to do so.[24]

In August 2012, Cellcom Liberia started Dual-Cell HSPA+ service in Liberia and its surroundings.[25]

In August 2012, Gmobile Mongolia announced the start of its DC-HSPA+ network. It is the first operator

in Mongolia to do so.[26]

In December 2012 Vodafone NZ announced the start of its DC-HSPA network roll-out, ahead of other

carriers.[27][28]

In October 2013, NOVAFONE Liberia started Dual-Cell HSPA+ service in Liberia and its surroundings.[29]

Marketing as mobile broadband[edit]

During 2007, an increasing number of telcos worldwide began selling HSDPA USB modems to provide

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",[30]

which is only attained under ideal

conditions. As a result these services can be slower than expected, when in fringe coverage indoors.

See also[edit]

Wikimedia Commons has

media related to HSDPA.

3GPP Long Term Evolution

Broadband Internet access

Cellular router

Evolution-Data Optimized

High-Speed Uplink Packet Access

High-Speed OFDM Packet Access

List of device bandwidths

List of HSDPA networks

Multi-band

Mobile broadband

Mobile broadband modem

UMTS

UMTS frequency bands

hsdpa

Documents