Along with the mobile communication industry’s fast development, each Standardization organization’s related standard research work even more aggressively is also carrying on. And, the HSPA achievement is situated between HSPA and the LTE one kind of technology, at present the 3GPP Standardization organization classifies initially it to the R7 series. This article embarks from the HSPA terminal category’s definition, discusses it and the HSPA terminal relations, as well as HSPA terminal new characteristic.
HSPA terminal classification situation
HSPA is HSPA(3GPPR6) downward evolution edition, is a technology which the ascending-descending ability strengthens, in the FDD system, the ascending-descending resources is separates processing, therefore here discusses the HSPA terminal category must carry on separately from the high and low two angles.
From standard definition’s angle, the HSPA downward traffic channels traffic channel is HS-DSCH, therefore the downward terminal category is also called “the HSDPA terminal category”, certainly here “the HSDPA terminal category” is different with in 3GPPR5 HSDPA. Similarly, the HSPA upward traffic channels traffic channel is E-DCH, therefore the upward terminal category may be called “the HSUPA terminal category”, is also different in 3GPPR6 “the HSUPA terminal category”.
According to the 3GPP25.306V730 definition, the HSDPA(FDD) terminal altogether divides into 16 kinds, as shown in Table 1.
Table 1 HSDPA terminal category and parameter data sheet
As seen in Table 1, HSPA the terminal completely backward compatible HSDPA terminal, Category1~12 is the HSDPA terminal definition. The HSPA terminal’s standard still in further revised, has the possibility also to have other categories the terminal.
According to the 3GPP25.306V730 definition, the HSUPA(FDD) terminal altogether divides into 7 kinds, as shown in Table 2.
Table 2 HSDPA terminal category and parameter data sheet
As seen in Table 2, HSPA the terminal completely backward compatible HSUPA terminal, Category1~6 is the HSUPA terminal definition. Similarly, HSPA terminal standard still in further revised, also has the possibility also to have other categories the terminal.
Affects the HSPA terminal performance the essential essential factor
Table 1 and Table 2 have listed the peak value speed which as well as the influence peak value speed primary factor in detail the different category’s terminal corresponds, affects the HSPA terminal performance the key aspect mainly to have the following several aspects.
1. modulation system
HSPA may use the QPSK,16QAM,64QAM three modulation systems. QPSK each mark represents 4bit on behalf of 2bit,16QAM each mark, but 64QAM each mark represents 6bit. Therefore as a result of modulation system’s difference, each mark representative’s information content also has the difference.
As seen in Table 1, the Category1~10 peak value speed is calculates under the 16QAM modulation system, is higher than only supports QPSK debug mode Category11~12 the peak value speed, but after Category13~14 uses 64QAM the modulation, the front 12 kinds must be higher.
As seen in Table 2, speed higher Category7 uses the 16QAM modulation, but other 6 kinds only support the QPSK modulation system.
2. antenna way
the 3GPPR6 standard and the beforehand edition use traditional the dual-mode antenna, but HSPA uses the brand-new MIMO(2X2) disposition, the relevance does not raise the system efficiency enormously using the antenna, specially in the signal environment good situation, each antenna may transmit the different information, realizes the peak value speed double.
As seen in Table 1, disposed the MIMO terminal Category15~16 peak value speed to be biggest, its computational process was as follows.
Category15 the biggest transmission block which may transmit in list TTI(2ms) in is 23370bit, therefore its peak value speed is: 23370bit/2ms×2=23.4Mbit/s.
Category16 the biggest transmission block which may transmit in list TTI(2ms) in is 27952bit, therefore its peak value speed is: 27952bit/2ms×2=28Mbit/s.
Here must explain a point: In the above two formula behind rides 2, is represents 2 to send the MIMO antenna load bearing different information, therefore the peak value speed turns time.
3. support biggest symbol number
(1)HSDPA
HSDPA uses fixed SF=16 the code road, the single plot takes SF=16 besides the public channel the symbol, the HSDPA most greatly available symbol number is 15, may know by Table 1, 16 kind of terminal support’s biggest symbol number respectively is 5, 10, 15. Based on the WCDMA correspondence principle, the signal from the source encoding to the channel coding, carries on the wide frequency to modulate again to the 3.84Mchips/s band width.
Uses the QPSK modulation, HSDPA Shan Ma limit through-put capacity is: 3840/16×2=480kbit/s.
Uses the 16QAM modulation, HSDPA Shan Ma limit through-put capacity is: 3840/16×4=960kbit/s.
Uses the 64QAM modulation, HSDPA Shan Ma limit through-put capacity is: 3840/16×6=1440kbit/s.
Obviously the HSDPA speed with the code magical skill which may use is closely related, in the other condition consistent situation, the use code magical skill are more, can achieve the peak value speed is bigger.
(2)HSUPA
Upward UE may use the code magical skill the speed correlation which and needs to transmit with own channel environment, it uses variable factor SF respectively is 64, 32, 16, 8, 4, 2, simultaneously uses many yard road transmissions. May know by Table 2, in other conditions (SF, TTI, the modulation system) in the same situation, 4 yard road transmission’s speed is higher than 2 yard road transmissions obviously the speed.
4. soft channel capacity
In view of the HSDPA 16 kind of terminals, the standard has defined the corresponding soft channel capacity separately: The HARQ hypothesized IR buffer, namely HS-DSCH can transmit total information content.
Mixes ARQ is one of HSDPA key technologies, after it completes the channel coding an output bit number and maps the HS-PDSCH physics channel set always a bit number to match, the HARQ function by the redundant edition (RV) parameter control, mixes a ARQ output bit precise establishment to rely on an input bit number, an output bit number and the RV parameter.
The HARQ function includes 2 speed matches and a hypothesized IR buffer, is also called the soft channel capacity, had decided mixes ARQ the first speed match. The soft channel capacity will affect the network side use transmission form (RV), and will affect UE to a certain extent the through-put capacity, this capacity will be bigger corresponds the effective transmission information content to be bigger, the UE speed will be higher, this may obtain the confirmation from Table 1.
5. smallest TTI gap
HSDPA uses the resource sharing the way, frame size TTI is 2ms, under the code way, each TTI may simultaneously hold 4 users. In the resource distribution condition permission’s situation, UE may take the resources, simultaneously each TTI has the message routing, may realize the availability of resources maximization, but UE in takes TTI in the situation not to be able to transmit the data, this will waste the system resources. For example, the smallest TTI gap is 2 or 3 UE and the TTI gaps is 1 UE compares, when transmission same information content, because the former holding time is the latter 2 or 3 times, therefore the former’s speed is the latter 1/2 or 1/3. Therefore, the smallest TTI gap also has the very tremendous influence to the terminal performance.
The smallest TTI gap is smaller, representative may the transmitter data opportunity be more, the achievable speed is bigger. Performance low handset when net, high Inter-TTI will cause the network side base depot frequency spectrum to reduce using the efficiency.
Affects the HSPA development the key technologies
Above listed has affected the HSPA terminal the essential essential factor, but how in fact to process these essential factors, how to differentiate the difference between various categories terminal, the key decided by a series of new technologies.
Since the volume, has consumed questions and so on electricity has puzzled one of terminal development important questions. It is well known, the 3G terminal power consumption slightly is higher than the 2G terminal, this and the 3G technology’s complexity concerns. the 3G CDMA technology is complex, the baseband data process load is big, the radio frequency power amplifier’s linearity request is very high, causes the 3G terminal baseband processing chip and the radio frequency chip set’s power consumption increases relatively; HSPA needs compared to a HSPA more complex baseband and the radio frequency technology, and, dynamic technical and so on power and code resources adjustment, 16QAM/64QAM/MIMO introductions cause HSPA to have compare a HSPA higher power loss; The transmission speed is quicker, is higher to the handset antenna’s performance requirement, consumes the electric quantity is also bigger. Therefore, looking from the signaling processing angle, the HSPA terminal needs to consider the energy conservation province electricity fully the correlation technique.
Along with all-IP idea’s strengthening, HSPA will become entire IP, the entire service operation network key technologies, therefore it needs to break through original HSPA to support the BE service purely the limitation, realizes pronunciation (VoIP), video frequency (VT), high speed downloading and so on multimedia service fusions.
Synthesizes the above two main points, the new technology which the HSPA terminal uses mainly has the following several kinds.
1.DPCCH time slot change
According to the 3GPP25.211 standard’s definition, original upward DPCCH altogether has 6 kind of time slot structures, each time slot has the pilot frequency bit, TFCI, TPC as well as the FBI four bit territories: The pilot frequency bit uses for in the receiving end to carry on the channel estimate; TFCI instructs the current frame the transmission speed; The TPC transmission carries on the power control order which the downlink power control needs; When downlink use closed loop launch diversity needs the FBI bit.
But after using HS-DSCH, may realize the blind decoding, does not need TFCI the speed instruction. In addition, when non-closed loop does not need to use FBI, therefore this time effective bit is TPC, Pilot. The additional time slot form divides into DPCCH 10bit 6bit Pilot,4bit TPC, guaranteed that the effective bit unit, reduces the nonessential bit transmission, realizes the resources effective use.
2.UL-DTX
With WCDMA the beforehand edition - DPCH transmission compares, UL_DTX(UplinkDiscontinuousTransmission) only exists in the DPDCH data channel, but in R7, has introduced under the upward control channel DPCCH UL_DTX function, the UL-DTX application may reduce the terminal at the same time the power consumption, on the other hand may also reduce to the upward disturbance.
3.HS-SCCHless Transmissions
In the 3GPPR5/R6 edition, the HS-SCCH channel is the downward physical sharing channel, its introduction is the physical level signaling which needs for the load bearing HS-PDSCH channel. Its wide frequency factor is 128, each 2ms after-crops the corresponding dispatch instruction to the corresponding terminal, but dispatches the situation must refer to HS-SCCH the disposition number: When only matches one, multiuser can only share the HS-PDSCH channel through the multiplying form, can only serve in TTI for a user. It most may dispose 4, namely may dispatch 4 users in list TTI. Therefore, the HS-SCCH use can consume the very big symbol and the power resources, cuts system’s use efficiency.
Has introduced the HS-SCCHlessTransmissions pattern in the 3GPPR7 edition, on the one hand partial signaling pack load bearing on the HS-PDSCH high-speed channel, on the other hand uses the blind demodulation in the UE end the way, has saved the HS-SCCH symbol and the power resources enormously, raised the system efficiency.
4. enhancement F-DPCH
In order to optimize the system use the efficiency, the 3GPPR6 standard has introduced F-DPCH (Fractional Dedicated Physical Channel), mainly uses for to transmit the downward merit to control instruction TPC, its biggest advantage is multiuser (most 10 users) may share SF=256 the code road, but it is not substitutes A-DPCH (a-DPCH disposition to use the HSDPA service for each user), the network side acts according to the terminal the support situation, may also choose F-DPCH, may also choose A-DPCH.
In 3GPPR7, any RL corresponds corresponding F-DPCH, simultaneously the original A-DPCH load bearing’s signaling shifts to HS-DSCH on the load bearing, because HSDPA compares the R99 speed to be higher, therefore the SRB load bearing can reduce the service establishment on HS-DSCH the latency.
5. enhancement Cell_FACH
Considered the data load bearing the efficiency, 3GPPR7 has introduced enhancement Cell_FACH. Its transmission channel no longer is original DCH, but is high speed HS-DSCH, the capacity increases, the latency reduces.
6. other technologies
In other editions, considered the terminal questions and so on power consumption, processing complexity, volume, technologies and so on MIMO, 64QAM are only considered in the network side, but from promotes the terminal performance, to raise the peak value speed the angle, these network side’s new technology also in the terminal side consideration.
During the coordination applies a these technology, like RLCPDU size and so on level two functions, also needs to make the adjustment correspondingly.
Summary
This article introduced the HSPA terminal’s category as well as affects the terminal performance the essential essential factor, simultaneously unified the terminal performance the promotion as well as the HSPA service goal gives has affected the HSPA terminal the key technologies. The HSPA terminal still in further developed, but also has the possibility which the new terminal category appears, the correlation technique also needs the further consummation.
