High Speed Packet Access

High Speed Packet Access (HSPA) is a collection of two mobile telephony protocols High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA), that extend and improve the performance of existing WCDMA protocols. A further standard, Evolved HSPA (also known as HSPA+), is soon to be released.

Overview

HSDPA 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 JuneApril 2008, the Global mobile Suppliers Association (GSA) reported that 90.88 percent of all WCDMA networks are upgraded to HSDPA. 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 of fixed broadband.

Majority of deployments provide up to 7.2 Mbit/s in the down-link and 14 Mbit/s will be available as soon as the devices are available in the market.

Voice calls are usually prioritized over data transfer. The Australian provider, Telstra uses up to 14.4 Mbit/s nationwide. The Croatian VIPnet network supports the speed of 7.2 Mbit/s in down-link as does Rogers Wireless in Canada. 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 7.2 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.

See full list of HSDPA networks committed and in service.

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. 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. 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.

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 5MHz 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. An HSPA+ network can theoretically support up to 28Mbit/s and 42Mbit/s with a single 5MHz 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 5MHz to 10MHz. Besides the throughput gain from double the bandwidth, some diversity and joint scheduling gains can also be expected. 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. 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.

http://en.wikipedia.org/

Global mobile Suppliers Association

The Global mobile Suppliers Association (GSA) is an organization dedicated to the promotion of the GSM, 3G, WCDMA, HSPA and LTE mobile phone standards worldwide.

GSA represents leading GSM/3G/WCDMA-HSPA/LTE suppliers worldwide, covering close to 100% of mobile market share. GSA delivers authoritative facts, market intelligence, objective analysis and information. Member companies include AnyDATA, Aeroflex, Comsys Communications, Ericsson, Nokia Siemens Networks, Panasonic, Qualcomm, ST-NXP Wireless, and Telcordia.

It is not to be confused with the GSM Association (GSMA), another organization with similar stated goals.

http://en.wikipedia.org/

E-UTRA

Evolved Universal Terrestrial Radio Access (E-UTRA) is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. E-UTRA is the successor to HSDPA and HSUPA technologies specified in 3GPP releases 5, 6 and 7. Unlike HSPA, LTE's E-UTRA is an entirely new air interface system, unrelated to and incompatible with W-CDMA.

Features

E-UTRA has the following features:

* Flexible bandwidth usage with 1.25 MHz to 20 MHz bandwidths. By comparison, W-CDMA uses fixed size 5 MHz chunks of spectrum.
* Increased spectral efficiency at 2-4 times more than in 3GPP (HSPA) release 6
* Peak download rates of 326.4 Mbit/s for 4x4 antennas, 172.8 Mbit/s for 2x2 antennas for every 20 MHz of spectrum.
* Peak upload rates of 86.4 Mbit/s for every 20 MHz of spectrum.
* Sub-5ms latency for small IP packets.

Design

E-UTRA uses orthogonal frequency-division multiplexing (OFDM) and multiple-input multiple-output (MIMO) antenna technology to support more users, higher data rates and lower processing power required on each handset.

Rationale for E-UTRA

E-UTRA was designed to achieve the goals set by the 3GPP LTE project. The improvements in performance allow wireless operators to offer quadruple play services - voice, high-speed interactive applications including large data transfer and feature-rich IPTV with full mobility.

Although UMTS, with HSDPA and HSUPA, delivers high data transfer rates, wireless data usage is expected to increase significantly over the next few years. The emergence of competitive technologies, such as WiMAX, is driving operators to upgrade their networks to support better data rates. E-UTRA also dramatically improves the capacity of the network.

As a part of 3GPP Release 8, E-UTRA is designed to provide a single evolution path for both UMTS and EV-DO service providers, providing increases in data speeds, and spectral efficiency, and allowing the provision of more functionality.

Technology demos

* In September 2007, NTT Docomo demonstrated E-UTRA data rates of 200 Mbit/s with power consumption below 100mW during the test.

* In April 2008, LG and Nortel demonstrated E-UTRA data rates of 50 Mbit/s while travelling at 110km/hr.

http://en.wikipedia.org/

High-Speed Downlink Packet Access

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 or 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.

Technology

The High-Speed Downlink Shared Channel (HS-DSCH) lacks two basic features of other W-CDMA channels—variable spreading factor and fast power control. Instead, it delivers the improved downlink performance using adaptive modulation and coding (AMC), fast packet scheduling at the base station, and fast retransmissions from the base station, known as hybrid automatic repeat-request (HARQ).

Hybrid automatic repeat-request (HARQ)

HARQ uses incremental redundancy, where user data is transmitted multiple times using different codings. When a corrupted packet is received, the user device saves it and later combines it with the retransmissions, 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.

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 periodically 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 modulation almost doubles data throughput rates. With 5 Code allocation, QPSK typically offers up to 1.8 Mbit/s peak data rates, while 16QAM 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. Theoretically, HSDPA can give throughput up to 14.0 Mbit/s.

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.

Along with the HS-DSCH channel, three new physical channels are also introduced: 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.

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. It will introduce 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.

After HSPA Evolved, the roadmap leads to E-UTRA (Previously "HSOPA"), a technology under development for specification 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. For details, see.

Adoption

As of May 25, 2007, 102 HSDPA networks have commercially launched mobile broadband services in 55 countries. Nearly 40 HSDPA networks support 3.6 Mbit/s peak downlink data throughput. A growing number are delivering 7.2 Mbit/s peak data downlink, leveraging new higher-speed devices coming into the market. One network has been declared as “14.4 Mbit/s (peak) ready” and several others will have this capability by end 2007. The first commercial HSUPA uplink network is launched, with several more set to follow in 2007.

This protocol is a relatively simple upgrade where UMTS is already deployed.

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 of 2008, Bell Canada and Telus announced a joint plan to expand their current shared EVDO/CDMA network to include HSDPA. Singapore is currently the only country boasting nationwide HSDPA with speeds up to 7.2Mbps down and 2.0Mbps up. The 3 operators are namely MobileOne, SingTel and StarHub.

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", 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.

http://en.wikipedia.org/