The afterward is from 3GPP TR 25.872 – Technical Specification Group Radio Access Network; HSDPA Multipoint Transmission:

HSPA based adaptable internet offerings are acceptable actual accepted and abstracts acceptance is accretion rapidly. Consequently, HSPA has amorphous to be deployed on added than one address antenna or added than one carrier. As an example, the distinct corpuscle downlink MIMO (MIMO-Physical layer) affection was alien in Release 7. This affection accustomed a NodeB to address two carriage blocks to a distinct UE from the aforementioned corpuscle on a brace of address antennas appropriately convalescent abstracts ante at aerial geometries and accouterment a beamforming advantage to the UE in low geometry conditions. Subsequently, in Release-8 and Release-9, the bifold corpuscle HSDPA (DC-HSDPA) and bifold bandage DC-HSDPA appearance were introduced. Both these appearance acquiesce the NodeB to serve one or added users by accompanying operation of HSDPA on two altered carrier frequencies in two geographically overlapping cells, appropriately convalescent the user acquaintance above the absolute corpuscle advantage area. In Release 10 these concepts were continued so that accompanying transmissions to a distinct UE could action from four beef (4C-HSDPA).

When a UE avalanche into the softer or bendable handover advantage arena of two beef on the aforementioned carrier frequency, it would be benign for the non-serving corpuscle to be able to agenda packets to this UE and thereby convalescent this accurate user’s experience, abnormally back the non-serving corpuscle is partially loaded. MultiPoint HSDPA allows two beef to address packets to the aforementioned UE, accouterment bigger user acquaintance and arrangement amount balancing. MultiPoint HSDPA can accomplish on one or two frequencies.

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There is additionally an absorbing Qualcomm Whitepaper on accompanying affair that is accessible to appearance and download here. The afterward is from that whitepaper:

The simplest anatomy of Multipoint HSPA, Distinct Abundance Bifold Corpuscle HSPA (SFDC-HSPA), can be apparent as an addendum to the absolute DC-HSPA feature. While DC-HSPA allows scheduling of two absolute carriage blocks to the adaptable accessory (UE) from one area on two abundance carriers, SFDC-HSPA allows scheduling of two absolute carriage blocks to the UE from two altered sectors on the aforementioned carrier. In added words, it allows for a primary and a accessory confined corpuscle to accompanying accelerate altered abstracts to the UE. Therefore, the above aberration amid SFDC-HSPA and DC-HSPA operation is that the accessory carriage block is appointed to the UE from a altered area on the aforementioned abundance as the primary carriage block. The UE additionally needs to accept accept assortment (type 3i) to abolish arrest from the added corpuscle as it will accept abstracts on the aforementioned frequecny from assorted confined cells.Figure 1 llustrates the high-level abstraction of SFDC-HSPA.

In the case area the two sectors complex in Multipoint HSPA manual accord to the aforementioned NodeB (Intra-NodeB mode), as illustrated in Figure 2, there is alone one manual chain maintained at the NodeB and the RNC. The chain administration and RLC bandage operation is about the aforementioned as for DC-HSPA.

In the case area the two sectors accord to altered NodeBs (Inter-NodeB mode), as illustrated in Figure 2, there is a abstracted manual chain at anniversary NodeB. RLC bandage enhancements are bare at the RNC forth with added breeze ascendancy on the Iub interface amid RNC and NodeB in adjustment to abutment Multipoint HSPA operation above NodeBs. These enhancements are discussed in added detail in Section 4. In both modes, accumulated acknowledgment advice (CQI and HARQ-ACK/ NAK) needs to be beatific on the uplink for both abstracts streams accustomed from the confined cells. On the uplink, the UE sends CQIs apparent on all sectors application the bequest approach structure, with timing accumbent to the primary confined cell.

When two carriers are accessible in the network, there is an added amount of abandon in the abundance domain. Bifold Abundance Bifold Corpuscle HSPA (DFDC-HSPA) allows base both abundance and spatial domains by scheduling two absolute carriage blocks to the UE from two altered sectors on two altered abundance carriers. For a DC-HSPA able UE, this is agnate to accepting absolute confined beef on the two abundance carriers. In Figure 3, UE1 is in DC-HSPA mode, admitting UE2 is in DFDC-HSPA mode.

Dual Abundance Four-Cell HSPA (DF4C-HSPA) can be apparent as a accustomed addendum of DFDC-HSPA, acceptable for networks with UEs accepting four receiver chains. DF4C-HSPA allows use of the four receiver chains by scheduling four absolute carriage blocks to the UE from two altered sectors on two altered abundance carriers. DF4C-HSPA is illustrated in Figure 4.

Like SFDC-HSPA; DFDC-HSPA and DF4C-HSPA can additionally be intra-NodeB or inter-NodeB, consistent in an appulse on manual chain management, Iub breeze ascendancy and the RLC layer.

Advantages of Multipoint transmission:

* Corpuscle Bend Achievement Improvement

* Amount acclimation above sectors and abundance carriers

* Leveraging RRU and broadcast NodeB technology

Multipoint HSPA improves the achievement of corpuscle bend users and helps antithesis the amount alterity above adjoining cells. It leverages avant-garde receiver technology already accessible in adaptable accessories accordant with Release 8 and above to accomplish this. The arrangement appulse of Multipoint HSPA on the arrangement ancillary is primarily bound tocomputer application upgrades affecting the high layers (RLC and RRC).