UMTS did not stop at Release 99. Each later 3GPP release added features on top of HSDPA and HSUPA. Most of them serve one of three goals. The first is a higher peak rate, the second is a lower cost of keeping a packet user connected, and the third is the use of more carriers at the same time. This page lists the main features release by release, from Release 7 to Release 10. It then adds the releases before and after that range, shows how the peak rate grew, and explains how you can check the release of a feature yourself.

• Which main features did Release 7 to Release 10 add ?
• What came before Release 7 ?
• What did Release 11 and later add ?
• How did the peak rate grow from release to release ?
• How can you check which release introduced a feature ?
• Reference

Which main features did Release 7 to Release 10 add ?

Release 7 to Release 10 is the period in which HSPA grew into HSPA+. Release 5 and Release 6 had already defined the shared downlink channel and the enhanced uplink. The four releases below reuse those channels and extend them in modulation, antennas and carriers. Let's take them one release at a time, because each release builds on the one before it.

Release 7

Release 7 raises the peak rate within one 5 MHz carrier, and it also reduces the overhead of a user who is connected but mostly idle. The list below covers both goals.

• Higher Order Modulation (DL 64 QAM, UL 16 QAM)
• CPC (Continous Packet Connectivity, DTX + DRX)
• Enhanced F-DPCH
• Improved L2 (for Higher downlink data rate)
• Enhanced Cell_FACH for downlink
• Downlink MIMO

64QAM carries six bits per HS-PDSCH symbol instead of four with 16QAM, and 16QAM on E-DCH carries twice the bits of QPSK. Downlink MIMO sends two transport blocks on the same channelization codes from two transmit antennas. CPC is the connectivity part. With uplink DTX, the UE stops sending the DPCCH continuously. With downlink DRX, the UE stops monitoring the HS-SCCH in every subframe. CPC also includes HS-SCCH-less operation, in which the first transmission of a small packet is sent without an HS-SCCH. The Enhanced F-DPCH adds F-DPCH slot formats. Each slot format puts the TPC field at a different position in the slot, as Table 16C of TS 25.211 shows. Improved L2 introduces MAC-ehs, with segmentation in the Node B, and flexible RLC PDU sizes for RLC AM. Enhanced CELL_FACH lets a UE in CELL_FACH state receive the HS-DSCH instead of the FACH.

Release 8

Release 8 combines the Release 7 features and adds the second carrier. It also completes the Enhanced CELL_FACH work for the uplink, so both directions of a CELL_FACH user can use HSPA channels.

• Dual Cell HSDPA
• Combination of 64 QAM and MIMO
• Improved L2 (for Higher uplink data rate)
• Enhanced Cell_FACH for uplink
• CS over HSPA
• Serving Cell Change Enhancement
• HS-DSCH Reception in Cell FACH

Dual Cell HSDPA lets the UE receive two HS-DSCH transport channels on two adjacent carriers at the same time. Each carrier keeps its own HARQ entity, but one MAC-ehs entity schedules both of them. In the uplink, Enhanced Cell_FACH lets the UE send on a common E-DCH resource rather than on the RACH message part. Note one detail on the last item. HS-DSCH reception in CELL_FACH itself was introduced with Enhanced CELL_FACH in Release 7. Release 8 adds DRX for that reception and HS-DPCCH feedback in CELL_FACH state.

Release 9

Release 9 takes the dual cell idea further in two directions. It brings the second carrier to the uplink, and it allows the two downlink carriers to sit in different frequency bands.

• Dual Cell HSUPA
• Dual Band HSDPA
• Dual Cell HSDPA + MIMO
• 2ms TTI Uplink range extension

Dual Cell HSUPA is called Dual Cell E-DCH operation in the specification. The UE sends two E-DCH transport channels on two uplink carriers. Dual Band HSDPA is DC-HSDPA with the two carriers in two frequency bands. Dual Cell HSDPA + MIMO allows MIMO on one or both of the two downlink cells. The HS-DPCCH then reports the CQI of the two cells in turn, as CQI1 and CQI2.

Release 10

Release 10 has only one main UMTS feature in the list, but it doubles the downlink carrier count again. From this release on, HSPA growth comes mainly from more carriers rather than from a new modulation.

• Four Carrier HSDPA

With Four Carrier HSDPA, the UE has one serving HS-DSCH cell and up to three secondary serving HS-DSCH cells. The four carriers can be spread over one or two frequency bands. Each cell can also run MIMO, and the DRX status is common for all serving HS-DSCH cells.

• Release 7 works inside one carrier : 64QAM, 16QAM uplink and MIMO raise the rate, and CPC lowers the cost of an idle connection.
• Release 8 to Release 10 add carriers : two downlink carriers in Release 8, two uplink carriers and two bands in Release 9, four downlink carriers in Release 10.
• CELL_FACH users get HSPA channels too : HS-DSCH reception in Release 7, then common E-DCH, DRX and HS-DPCCH feedback in Release 8.

What came before Release 7 ?

The Release 7 list above assumes that HSDPA and HSUPA already exist. So it helps to know where each basic channel came from before reading the list. The releases before Release 7 built that base in three steps.

Release 99 is the first UMTS release. It defines the dedicated channels DCH and DPCH, the common channels such as FACH, RACH and PCH, and the RRC states CELL_DCH, CELL_FACH, CELL_PCH and URA_PCH. All user data in Release 99 runs on these channels, and a high rate needs a low spreading factor on a dedicated code.

Release 5 introduces HSDPA. The HS-DSCH is a downlink transport channel shared by several UEs, with a 2 ms subframe, HARQ in the Node B and 16QAM in addition to QPSK. The MAC-hs entity for it sits in the Node B, so scheduling and retransmission are close to the air interface. In Release 5, only network controlled serving HS-DSCH cell changes are supported.

Release 6 introduces the E-DCH, which is the enhanced uplink or HSUPA. It uses HARQ and Node B scheduling in the uplink, with a 10 ms or 2 ms TTI. Release 6 also adds the F-DPCH, which carries only TPC commands and saves downlink codes for HSDPA users. The MICH for MBMS is added in the same release.

• Release 99 is dedicated channel based : DCH and DPCH carry the user data, and the rate depends on the spreading factor.
• Release 5 and Release 6 are the HSPA base : HS-DSCH in the downlink, E-DCH in the uplink, both with HARQ and Node B scheduling.
• F-DPCH is a Release 6 channel : the Enhanced F-DPCH of Release 7 extends it with more slot formats.

What did Release 11 and later add ?

UMTS work did not end with Four Carrier HSDPA. Release 11 to Release 15 still added HSPA features. The lists below come from the change history of TS 25.211, TS 25.213, TS 25.308 and TS 25.319. So each item is a CR title or close to one.

Release 11 is the last release with large rate features.

• Eight Carrier HSDPA - 8C-HSDPA
• Four branch MIMO - 4Tx-HSDPA
• Multiflow HSDPA, in which the UE receives data from two cells at the same time
• Uplink closed loop transmit diversity - UL CLTD
• Uplink MIMO and uplink 64QAM
• Further Enhancements to CELL_FACH

Release 12 to Release 15 focus on capacity, coverage and small cells rather than on the peak rate.

• Release 12 : DCH Enhancements, Enhanced Broadcast of System Information, UMTS Heterogeneous Networks enhancements, E-DCH decoupling, EUL coverage improvements, Further EUL enhancements, DPCCH2, and radio links without DPCH/F-DPCH
• Release 13 : Dual Carrier HSUPA enhancements for UTRAN CS, HSPA dual band uplink carrier aggregation, URA_PCH with seamless transition, Multiflow 3F-4C configuration and blind HARQ retransmissions for HSDPA
• Release 14 : Dual Cell E-DCH operation enhancements, enhanced TTI switching and HS-SCCH DRX operation in CELL_FACH state
• Release 15 : Simplified HS-SCCH type 1 operation

After Release 15, the UMTS specifications are mostly upgraded to the next release without technical change. For example, the change history of TS 25.308 records the Rel-16 to Rel-19 versions as upgrades without technical change.

• Release 11 is the peak of HSPA+ rates : eight downlink carriers, four branch MIMO and uplink MIMO all arrive in this release.
• Later releases target efficiency : DCH enhancements, HetNet support and TTI switching improve capacity and coverage rather than the peak rate.
• The specifications are still maintained : the current versions are Release 19, and TS 25.308 has had no technical change since Release 15.

How did the peak rate grow from release to release ?

A feature list does not tell you how much each feature is worth. The UE categories in TS 25.306 give a direct way to measure it. Each category states the largest transport block the UE can receive or send in one TTI. The peak physical layer rate is that size times the number of streams and cells, divided by 2 ms.

The table below applies that calculation to the highest category of each step. The rates are physical layer transport block rates. They include no RLC, MAC or IP overhead, so an application sees less.

Two patterns are clear in the table. Up to Release 8, the rate grows by modulation and by MIMO inside one carrier. The largest HS-DSCH transport block stops at 42192 bits with 64QAM, and after that every step comes from more streams or more cells. So Release 9 to Release 11 double the peak rate each time by doubling the carrier count. The uplink follows the same path more slowly, with 16QAM, a second carrier and finally uplink MIMO.

• One 5 MHz carrier tops out at 42.2 Mbps : 64QAM and two MIMO streams, category 20.
• Every later doubling comes from carriers : 84.4, 168.8 and 337.5 Mbps with 2, 4 and 8 cells, each with MIMO.
• These are layer 1 rates : the transport block rate before RLC, MAC and IP overhead.

How can you check which release introduced a feature ?

Feature lists like the one on this page often differ from one source to another, especially for small features. You can settle such a question yourself from the specification, because every 3GPP TS ends with a change history annex.

Each row of that annex is one CR. It gives the meeting, the CR number, the subject, and the old and new version of the specification. The first digit of the new version is the release. So if a CR titled "Introduction of ..." moves a specification from 8.2.0 to 8.3.0, that feature is a Release 8 feature. A CR that moves the specification to x.0.0 usually opens a new release with that feature.

For example, the change history of TS 25.308 shows "Introduction of Dual Cell HSDPA operation" at 8.2.0 to 8.3.0, and "Introduction of 4C-HSDPA" at 9.1.0 to 10.0.0. The change history of TS 25.211 shows "Introduction of 64QAM for HSDPA" at 7.0.0 to 7.1.0, and "Specification of HS-DSCH for Release 5 in 25.211" at 4.3.0 to 5.0.0.

Use the stage 2 specification first. TS 25.308 covers HSDPA and TS 25.319 covers the enhanced uplink, and their CR titles name the feature directly. The physical layer specifications TS 25.211 to TS 25.214 confirm the same release from the layer 1 side.

• The new version gives the release : a CR ending at 9.x.x belongs to Release 9.
• Stage 2 CR titles name the feature : search TS 25.308 or TS 25.319 for "Introduction of".
• Upgrade rows carry no feature : rows such as "Upgrade to Rel-17 version without technical change" only move the release number.

Reference

[1] 3GPP TS 25.308 v19.0.0 - HSDPA overall description, stage 2, and its change history

[2] 3GPP TS 25.319 v19.0.0 - Enhanced uplink overall description, stage 2, and its change history

[3] 3GPP TS 25.211 v19.0.0 - Physical channels and mapping of transport channels onto physical channels, FDD, and its change history

[4] 3GPP TS 25.213 v19.0.0 - Spreading and modulation, FDD, change history

[5] 3GPP TS 25.306 v19.0.0 - UE Radio Access capabilities, Table 5.1a and Table 5.1g