CN102196495B - Downlink data transmission method, system and equipment - Google Patents

Abstract

The invention discloses a downlink data transmission method, a downlink data transmission system and downlink data transmission equipment, which relate to the field of wireless communication and are used for improving data transmission reliability and saving air-interface resources. The method comprises that: a base station allocates physical resource blocks (PRB) to a terminal according to channel quality indicator (CQI) information reported by the terminal and the current volume of downlink data to be transmitted; the base station determines a first modulation and coding scheme (MCS) level, wherein the first MCS level is lower than a second MCS level which is an MCS level determined according to signal-to-interference and noise ratios (SINR) on each PRB allocated to the terminal; the base station searches for an MCS form and a transport block size (TBS) form to obtain a TBS corresponding to the first MCS level and the total number of the PRBs allocated to the terminal; and the base station transmits the downlink data of the TBSs to the terminal by utilizing the PRBs allocated to the terminal. By the method, the system and the equipment, the data transmission reliability can be effectively improved, the repeat probability of a hybrid automatic repeat request (HARQ) can be reduced, and the wasting of air-interface resources can be effectively reduced.

Description

Downlink data transmission method, system and equipment

Technical field

The present invention relates to wireless communication field, relate in particular to a kind of downlink data transmission method, system and equipment.

Background technology

In Long Term Evolution (LTE) system, physical radio resource piece (PRB) is basic resource allocation unit, is used for carrying out the resource distribution of Physical Downlink Shared Channel (PDSCH) and Physical Uplink Shared Channel (PUSCH).A PRB is defined as the N of time domain _Symb ^ULIndividual continuous OFDM (OFDM) symbol and the N of frequency domain _Sc ^RBIndividual continuous subcarrier, as shown in Figure 1.Descending N in the LTE system _Symb ^ULAnd N _Sc ^RBValue by table 1, provided.As shown in Table 1, under conventional CP, conventional PRB comprises 84 Resource Units (RE namely minimum resource granularity unit), a conventional PRB comprises 168 RE to (PRB Pair).

Table 1

While according to the LTE agreement, determining descending transmission block size (TBS), suppose under conventional CP, control area takies under the pilot-frequency expense condition of 3 OFDM symbols (being CFI=3), 2 antenna ports, each conventional PRB is to comprising 120 RE that can be used for business data transmission.

According to LTE system descending resource mapping rule, be used for the PRB of PDSCH transmission to being perforated, with transmission downlink physical broadcast channel (PBCH), primary synchronization channel (PSCH), auxiliary synchronization channel (SSCH), by the PRB that is perforated to being called punching PRB couple.In addition; for time-division Long Term Evolution (TD-LTE) system; because part RE is perforated with the transmission for the protection of interval time slot (GP), uplink special time slot (UpPTS) and PSCH, the OFDM symbolic number that descending special time slot (DwPTS) takies is less than conventional PRB couple.Particularly, there are four kinds of right use-cases of punching PRB, as shown in table 2.Wherein, the schematic diagram of four of TD-LTE system convention CP kinds of use-cases is referring to Fig. 2.

Table 2

The use-case numbering	The use-case content
		Case1	For frame structure 1 and frame structure 2,6 PRB in the middle of the bandwidth of subframe 0, part OFDM symbol are perforated for PBCH and SCH transmission
Case2	For all PRB of DwPTS in frame structure 2, the part running time-frequency resource is perforated for GP, UpPTS and transmits
		Case3	For frame structure 1 and frame structure 2,6 PRB in the middle of the bandwidth of subframe 5, part OFDM symbol is perforated for SSCH and transmits
Case4	For 6 PRB in the middle of the bandwidth of frame structure 2, subframe 1 and subframe 6, an OFDM symbol is perforated for PSCH and transmits

In the LTE system, definite scheme of descending TBS belongs to the equipment problem of implementation, and the LTE agreement is not done unified regulation.At present a kind of common scheme of really fixing capable TBS is as shown in Figure 3:

Step 1: PRB number and the position of being determined to distribute to terminal (UE) by the downlink resource distribution module.In the process that resource is distributed, at first according to the PRB number of the current transfer of data demand of UE and broad-band channel quality indication (CQI) (being the Signal to Interference plus Noise Ratio (SINR) of full bandwidth) estimation distribution, then according to subband CQI, further determine to distribute number and the position of PRB.

Step 2: descending AMC module is selected modulation coding mode (MCS) grade according to the locational time domain SINR of PRB that distributes for UE.What during base station selected MCS grade, use is to have carried out according to the CQI that UE reports the SINR on each PRB that revises.

Step 3: obtain MCS sign (MCS index) by the MCS selector, according to the mapping relations of MCS index and transmission block size sign (TBS index), table look-up and obtain TBS index.The mapping form of descending MCS index and TBS index is referring to table 3.

Step 4: by the PRB number N_PRB of TBS index and CU, according to (TBS index, the N_PRB) mapping relations with TBS, obtain the size of TBS by searching the TBS form.Wherein, the TBS form is referring to table 4.

Table 3

Table 4

Being described as follows of his-and-hers watches 4: TBS form one has 27 row, 110 row, a kind of TBS call number of each line display I _TBS(value from 0 to 26, corresponding to 29 kinds of MCS grades in table 3), the PRB number N of distribution is shown in each list _PRB(for the system bandwidth of 20MHz, from 1 to 110).For for simplicity, table 4 has provided N _PRBFrom 1 to 10 situation.

LTE agreement 36.213 regulations: for the special subframe configuration 0 and 5 of conventional CP, and special subframe configuration 0 and 4, the DwPTS of expansion CP can not transmit data.In other situation, DwPTS can transmitting downlink data.

When DwPTS transmission downlink service data, the processing method of terminal (UE) side is as follows:

Step 1:UE is from reading the MCS signaling I of 5 bits the DCI signaling _MCS

Step 2:UE by resource distribute the indication obtain current operable PRB number N ' _PRB

Step 3:UE calculates the PRB number N for searching the TBS form _PRB:

Step 4: according to the MCS form, pass through I _MCSObtain I _TBS, then according to TBS form and (I _TBS, N _PRB) to the mapping relations of TBS, determine TBS.

In realizing process of the present invention, the inventor finds in prior art to exist following technical problem:

In four kinds of use-case situations shown in table 2, the RE number that can be used for business data transmission, causes the actual bit rate of business datum to improve, thereby has reduced the detection performance of UE to this business datum greatly reducing with respect to conventional PRB, wasted interface-free resources, made a concrete analysis of as follows:

Present LTE agreement regulation, base station (eNodeB) when determining the TBS of business datum, be all according to conventional PRB to designing, consider punching PRB on impact.Below as an example of Case1 in table 2 example, describe: the PRB that supposes a routine to the available RE number that comprises as the available RE number that 120, one punching PRB centerings comprise be 62, so, distributing two PRB to (N _PRB=2) under condition, punch PRB pair with the right spectrum efficiency of conventional PRB and code check referring to table 5.As shown in Table 5: two PRB that distribute when the eNodeB scheduler to be all punching PRB to the time (above-mentioned situation in 1.4M bandwidth, subframe 0 time be bound to occur), under 17 kinds of MCS grades, actual bit rate is all greater than 0.93, even greater than 1, UE even makes a mistake to the detection hydraulic performance decline of business datum, make the reliability of business data transmission reduce, the HARQ that causes while making a mistake retransmits has wasted interface-free resources greatly.

Table 5

I TBS	TBS (N PRB＝2)	Q m	The right spectrum efficiency (2*120REs) of conventional PRB	The right code check (2*120REs) of conventional PRB	The right spectrum efficiency (2*62REs) of punching PRB	The right code check (2*62REs) of punching PRB
							0	32	2	0.2333	0.1167	0.4516	0.2258
1	56	2	0.3333	0.1667	0.6452	0.3226
							2	72	2	0.4000	0.2000	0.7742	0.3871
3	104	2	0.5333	0.2667	1.0323	0.5161
							4	120	2	0.6000	0.3000	1.1613	0.5806
5	144	2	0.7000	0.3500	1.3548	0.6774
							6	176	2	0.8333	0.4167	1.6129	0.8065
7	224	2	1.0333	0.5167	2.0000	1.0000
							8	256	2	1.1667	0.5833	2.2581	1.1290
9	296	2	1.3333	0.6667	2.5806	1.2903
							10	328	4	1.4667	0.3667	2.8387	0.7097
11	376	4	1.6667	0.4167	3.2258	0.8065
							12	440	4	1.9333	0.4833	3.7419	0.9355
13	488	4	2.1333	0.5333	4.1290	1.0323
							14	552	4	2.4000	0.6000	4.6452	1.1613
15	600	4	2.6000	0.6500	5.0323	1.2581
							16	632	6	2.7333	0.4556	5.2903	0.8817
17	696	6	3.0000	0.5000	5.8065	0.9677
							18	776	6	3.3333	0.5556	6.4516	1.0753
19	840	6	3.6000	0.6000	6.9677	1.1613
							20	904	6	3.8667	0.6444	7.4839	1.2473
21	1000	6	4.2667	0.7111	8.2581	1.3763
							22	1064	6	4.5333	0.7556	8.7742	1.4624

23	1128	6	4.8000	0.8000	9.2903	1.5484
							24	1192	6	5.0667	0.8444	9.8065	1.6344
25	1256	6	5.3333	0.8889	10.3226	1.7204
							26	1480	6	6.2667	1.0444	12.1290	2.0215

Summary of the invention

The embodiment of the present invention provides a kind of downlink data transmission method, system and equipment, be used to improving the reliability of transfer of data, saves interface-free resources.

A kind of downlink data transmission method, the method comprises:

Base station, according to channel quality indicator CQI information and the current downlink data amount waiting for transmission of terminal to report, is terminal distribution Physical Resource Block PRB;

The highest spectral efficiency that the current wireless channel can be supported is determined according to described CQI information in base station; The spectrum efficiency η of the actual use of down physical channel is determined in base station according to following formula _Used: η _Used=(1-λ ₂+ λ ₁λ ₂) η _{CQI_ini}T, wherein, η _{CQI_init}For the highest spectral efficiency that described current wireless channel can be supported, λ ₁The expression base station be in the PRB of terminal distribution punching PRB to the number of the Resource Unit RE that comprises and the conventional PRB ratio to the number of the RE that comprises, λ ₂The expression base station is the ratio of total number that PRB pair of PRB centering punching and the PRB of terminal distribution is right; This spectrum efficiency η _UsedLess than described highest spectral efficiency; Base station, by searching the MCS form, obtains the MCS grade corresponding to spectrum efficiency of the actual use of described down physical channel, and is a MCS grade by this MCS classification; The one MCS grade is less than the 2nd MCS grade, and the 2nd MCS grade is the MCS grade of determining according to the Signal to Interference plus Noise Ratio SINR on each PRB of terminal distribution;

Base station, by searching MCS form and transmission block size TBS form, obtains a MCS grade and reaches the corresponding TBS of total number for the PRB of terminal distribution;

Base station is utilized as the downlink data of the PRB of terminal distribution to the described TBS of terminal transmission.

A kind of wireless communication system, this system comprises:

Base station, for the channel quality indicator CQI information according to terminal to report and current downlink data amount waiting for transmission, be terminal distribution Physical Resource Block PRB; According to described CQI information, determine the highest spectral efficiency that the current wireless channel can be supported; According to following formula, determine the spectrum efficiency η of the actual use of down physical channel _Used: η _Used=(1-λ ₂+ λ ₁λ ₂) η _{CQI_init}, wherein, η _{CQI_init}For the highest spectral efficiency that described current wireless channel can be supported, λ ₁The expression base station be in the PRB of terminal distribution punching PRB to the number of the Resource Unit RE that comprises and the conventional PRB ratio to the number of the RE that comprises, λ ₂The expression base station is the ratio of total number that PRB pair of PRB centering punching and the PRB of terminal distribution is right; This spectrum efficiency η _UsedLess than described highest spectral efficiency; By searching the MCS form, obtain the MCS grade corresponding to spectrum efficiency of the actual use of described down physical channel, and be a MCS grade by this MCS classification; The one MCS grade is less than the 2nd MCS grade, and the 2nd MCS grade is the MCS grade of determining according to the Signal to Interference plus Noise Ratio SINR on each PRB of terminal distribution; By searching MCS form and transmission block size TBS form, obtain a MCS grade and reach the corresponding TBS of total number for the PRB of terminal distribution; Be utilized as the downlink data of the PRB of terminal distribution to the described TBS of terminal transmission; And will be included as total number of PRB of terminal distribution and the signaling of a MCS grade sends to terminal;

Terminal, for the total number according to described PRB and a MCS grade, determining needs the TBS that receives, and according to the TBS downlink data receiving of determining.

，Gai base station, a kind of base station comprises:

Resource allocation unit, MCS classification unit, TBS determining unit and data transmission unit;

Described resource allocation unit, for the channel quality indicator CQI information according to terminal to report and current downlink data amount waiting for transmission, be terminal distribution Physical Resource Block PRB;

Described MCS classification unit comprises: spectrum efficiency determining unit, spectrum efficiency adjustment unit and MCS table lookup unit;

Described spectrum efficiency determining unit, for determining according to described CQI information the highest spectral efficiency that the current wireless channel can be supported;

Described spectrum efficiency adjustment unit, for determining the spectrum efficiency η of the actual use of down physical channel according to following formula _Used: η _Used=(1-λ ₂+ λ ₁λ ₂) η _{CQI_init}, wherein, η _{CQI_init}For the highest spectral efficiency that described current wireless channel can be supported, λ ₁The expression base station be in the PRB of terminal distribution punching PRB to the number of the Resource Unit RE that comprises and the conventional PRB ratio to the number of the RE that comprises, λ ₂The expression base station is the ratio of total number that in the PRB of terminal distribution, PRB pair of punching and PRB are right; This spectrum efficiency η _UsedLess than described highest spectral efficiency;

Described MCS table lookup unit, for by searching the MCS form, obtain the MCS grade corresponding to spectrum efficiency of the actual use of described down physical channel, and be a MCS grade by this MCS classification; The one MCS grade is less than the 2nd MCS grade, and the 2nd MCS grade is the MCS grade of determining according to the Signal to Interference plus Noise Ratio SINR on each PRB of terminal distribution;

Described TBS determining unit, for by searching MCS form and transmission block size TBS form, obtain a MCS grade and reach the corresponding TBS of total number for the PRB of terminal distribution;

Described data transmission unit, be used to the PRB that the is utilized as terminal distribution downlink data to the described TBS of terminal transmission.

In the present invention, after base station is terminal distribution PRB according to the CQI information of terminal to report and current downlink data amount waiting for transmission, determine the little MCS grade of the 2nd MCS grade that beguine is determined according to the SINR on each PRB of terminal distribution, then by searching MCS form and transmission block size TBS form, obtain a MCS grade and reach the corresponding TBS of total number for the PRB of terminal distribution, and be utilized as the downlink data of the PRB of terminal distribution to this TBS of terminal transmission.Visible, in the present invention due to a MCS grade less than the 2nd MCS grade, the TBS that obtains according to a MCS grade is also just less than the TBS that obtains according to the 2nd MCS grade, the actual spectrum efficiency that reaches also just reduces during transmitting downlink data so, the also corresponding reduction of code check of adopting, and then improved the reliability of transfer of data, and reduced the probability that HARQ retransmits, effectively reduced the waste to interface-free resources.

The accompanying drawing explanation

Fig. 1 is the schematic diagram of Physical Resource Block in prior art;

Fig. 2 is the right schematic diagram of PRB that punches under TD-LTE system convention CP in prior art;

Fig. 3 is LTE system descending TBS constant current journey really schematic diagram in prior art;

The method flow schematic diagram that Fig. 4 provides for the embodiment of the present invention;

Fig. 5 is the realization flow schematic diagram of the embodiment of the present invention;

The system configuration schematic diagram that Fig. 6 provides for the embodiment of the present invention;

The architecture of base station schematic diagram that Fig. 7 provides for the embodiment of the present invention;

The terminal structure schematic diagram that Fig. 8 provides for the embodiment of the present invention.

Embodiment

The embodiment of the present invention provides a kind of downlink data transmission method, in this method, the code check that uses while reducing downlink data transmission by the MCS grade of adjusting the transfer of data employing, to improve data transmission credibility, reduce the HARQ retransmission probability, effectively avoid the waste to interface-free resources.

Referring to Fig. 4, the downlink data transmission method that the embodiment of the present invention provides specifically comprises the following steps:

Step 40: base station, according to channel quality indication (CQI) information and the current downlink data amount waiting for transmission of terminal to report, is terminal distribution Physical Resource Block (PRB);

Step 41: a MCS grade is determined in base station, and a MCS grade is less than the 2nd MCS grade, and the 2nd MCS grade is the MCS grade of determining according to the SINR on each PRB of terminal distribution;

Step 42: base station, by searching modulation coding mode MCS form and transmission block size (TBS) form, obtains a MCS grade and reaches the corresponding TBS of total number for the PRB of terminal distribution;

Step 43: the PRB that base station is utilized as terminal distribution is to the downlink data of the TBS that determines in terminal transmission step 42.

In step 41, base station determines that a MCS grade can adopt following two kinds of modes:

Mode one:

At first, the highest spectral efficiency that the current wireless channel can be supported is determined according to the CQI information that UE reports in base station;

Then, the highest spectral efficiency that base station can be supported according to wireless channel is determined the actual spectrum efficiency of using of current down physical channel (for example PDSCH), and this spectrum efficiency is less than described highest spectral efficiency.Make the real frequency spectrum efficiency that reaches by this spectrum efficiency of configuration mate with the highest spectral efficiency that wireless channel is supported;

Finally, base station, by searching the MCS form, obtains the corresponding MCS grade of spectrum efficiency of the actual use of current down physical channel, and is a MCS grade by this MCS classification.

Mode two:

At first, base station is according to be that time domain SINR on each PRB of terminal distribution selects the MCS grade, and that while selecting the MCS grade, use is the SINR on each PRB that CQI that base station reports according to UE has carried out correction;

Then, a grade of the MCS less than selected MCS grade is determined in base station, by this MCS classification, is a MCS grade.

Certainly, definite mode of a MCS grade is not limited to above-mentioned two kinds of modes, any determine less than the 2nd MCS grade and more than or equal to the mode of a MCS grade of MCS grade 0 all in protection scope of the present invention.

In aforesaid way one, the spectrum efficiency of the actual use of current down physical channel is determined in base station, can be in the following way:

The spectrum efficiency of the actual use of down physical channel: η is determined in base station according to following formula _Used=(1-λ ₂+ λ ₁λ ₂) η _{CQI_init}, wherein, η _{CQI_init}For the highest spectral efficiency that the current wireless channel can be supported, λ ₁The expression base station be in the PRB that distributes of UE punching PRB to the number of the Resource Unit (RE) that comprises and the conventional PRB ratio to the number of the RE that comprises, λ ₂The expression base station is the ratio of total number that in the PRB that distributes of UE, PRB pair of punching and PRB are right.

Adopt aforesaid way can guarantee real spectrum efficiency (η _Real) highest spectral efficiency (η that can support with the current wireless channel _{CQI_init}) coupling.Certainly, base station determines that the realization of the spectrum efficiency that current down physical channel can reach is not limited to aforesaid way, can also be to adopt the mode the such as directly spectrum efficiency of the actual employing of current down physical channel is turned down, the spectrum efficiency after adjustment need to be greater than 0.

After step 41, base station can send to terminal by being included as total number of PRB of terminal distribution and the signaling of a MCS grade; Terminal is according to total number and the MCS grade of the PRB that receives, and determining needs the TBS that receives, and the downlink data of the base station that receives being sent according to the TBS that determines carries out decoding, and then correct downlink data receiving.

Above-mentioned terminal is according to total number and the MCS grade of the PRB that receives, and determining needs the TBS that receives, and it is implemented as follows:

Terminal is N from downlink signaling, receiving the current PRB number that uses _PRB

Terminal, by searching the TBS table, obtains MCS grade and a N _PRBCorresponding TBS, needing to be defined as by this TBS the TBS that receives.

The present invention will be described below in conjunction with specific embodiment:

In the present embodiment, because TBS searches the TBS form by MCS grade and PRB number, obtain, so in the present invention, eNodeB adjusts the MCS grade according to actual conditions when sending, the UE side does not need to do independent processing.Specifically describe as follows: eNodeB is at the PRB number (N that keeps resource to distribute _{PE, PRB} ^Init) under constant condition, in the PRB that joins that scores, PRB is to being all under the condition that conventional PRB is right, data volume waiting for transmission is TBS _Init, will exist the punching PRB to the time data volume TBS waiting for transmission _InitBe adjusted into TBS ', make distributed punching PRB to only distribute conventional PRB couple, the spectrum efficiency under two kinds of conditions remains unchanged; The UE side is without unnecessary operation.Be the present invention do not need the LTE agreement for the punching PRB to doing independent regulation.

In the following description, suppose TBS _InitThe descending data volume that needs transmission, N _{PE, PRB} ^NormalAnd N _{RE, PRB} ^PuncRepresent respectively a conventional PRB to the punching RE number of PRB to comprising, λ ₁Represent that a punching PRB is to the RE number that comprises and the conventional PRB ratio to the RE number that comprises, namely

Suppose N _{PRB, all_normal}All PRB that are illustrated in distribution to be all conventional PRB under condition, the number of the CQI that reports according to UE of the eNodeB scheduler PRB that should distribute, N _{PRB, used}The number of the PRB of expression eNodeB scheduler actual allocated (wherein, comprises N _{PRB, punc}Individual punching PRB to and N _{PRB, used}-N _{PRB, punc}Individual conventional PRB to), the note λ ₂PRB pair of expression punching with total PRB of actual allocated ratio to number, namely ${\mathrm{\λ}}_2=\frac{N_{\mathrm{PRB},\mathrm{punc}}}{N_{\mathrm{PRB},\mathrm{used}}}.$

Concrete steps are referring to Fig. 5:

Start (Begin):

The CQI that step 50:eNodeB reports according to UE determines that the highest spectral efficiency that the current wireless channel can be supported is η _{CQI_init}(being target spectrum efficiency);

Step 51:eNodeB is according to η _{CQI_init}With data volume TBS waiting for transmission _InitDetermine that needing the number of the PRB that distributes is N _{PRB, all_normal}(suppose the PRB that comprises in the PRB that distributes to be all conventional PRB to);

Step 52:eNodeB keeps the number (N of the PRB that distributes _{PRB, all_normal}) constant, consider to exist punching PRB on impact, according to η _Used=(1-λ ₂+ λ ₁λ ₂) η _{CQI_init}Determine the spectrum efficiency (η of the actual use of PDSCH _Used), make by configuration η _UsedAnd make this moment PDSCH real frequency spectrum efficiency (η _Real) and target spectrum efficiency (η _{CQI_init}) coupling.Concrete derivation is as follows:

The PRB that note eNodeB actual needs distributes is N to number _{PRB, used}(number that guarantees PRB is constant, namely meets N _{PRB, used}=N _{PRB, all_normal}), wherein comprise N _{PRB, punc}Individual punching PRB to and N _{PRB, all_normal}-N _{PRB, punc}Individual conventional PRB couple, the number that PRB pair of note punching and total PRB of actual allocated are right has following ratio relation:

${\mathrm{\λ}}_2=\frac{N_{\mathrm{PRB},\mathrm{punc}}}{N_{\mathrm{PRB},\mathrm{all}\_\mathrm{normal}}}.$

In order to pass through configuration η _UsedGuarantee the real frequency spectrum efficiency (η of PDSCH _Real) and target spectrum efficiency (η _{CQI_init}) coupling, namely meet following relational expression:

${\mathrm{\η}}_{\mathrm{COI}\_\mathrm{init}}=\frac{{\mathrm{TBS}}_{\mathrm{init}}}{N_{\mathrm{RE},\mathrm{PRB}}^{\mathrm{Normal}}\×N_{\mathrm{PRB},\mathrm{all}\_\mathrm{normal}}}\≈\frac{{\mathrm{TBS}}^{\′}}{N_{\mathrm{RE},\mathrm{PRB}}^{\mathrm{Normal}}\×(N_{\mathrm{PRB},\mathrm{all}\_\mathrm{normal}}-N_{\mathrm{PRB},\mathrm{punc}})+N_{\mathrm{RE},\mathrm{PRB}}^{\mathrm{Punc}}\×N_{\mathrm{PRB},\mathrm{punc}}}={\mathrm{\η}}_{\mathrm{Real}}---\left(1\right)$

As can be known by following formula:

$\frac{{\mathrm{TBS}}^{\′}}{{\mathrm{TBS}}_{\mathrm{init}}}\≈\frac{N_{\mathrm{RE},\mathrm{PRB}}^{\mathrm{Normal}}\×(N_{\mathrm{PRB},\mathrm{all}\_\mathrm{normal}}-N_{\mathrm{PRB},\mathrm{punc}})+N_{\mathrm{RE},\mathrm{PRB}}^{\mathrm{Punc}}\×N_{\mathrm{PRB},\mathrm{punc}}}{N_{\mathrm{RE},\mathrm{PRB}}^{\mathrm{Normal}}\×N_{\mathrm{PRB},\mathrm{all}\_\mathrm{normal}}}$

$=\frac{(N_{\mathrm{PRB},\mathrm{all}\_\mathrm{normal}}-N_{\mathrm{PRB},\mathrm{punc}})+{\mathrm{\λ}}_1\·N_{\mathrm{PRB},\mathrm{punc}}}{N_{\mathrm{PRB},\mathrm{all}\_\mathrm{normal}}}=1-{\mathrm{\λ}}_2+{\mathrm{\λ}}_1\·{\mathrm{\λ}}_2---\left(2\right)$

According to the data volume TBS ' of actual needs transmission and the N that distributes _{PRB, all_normal}Individual PRB, determine the spectrum efficiency η of the actual use of current PDSCH _Used, be shown below:

${\mathrm{\η}}_{\mathrm{Used}}=\frac{{\mathrm{TBS}}^{\′}}{N_{\mathrm{RE},\mathrm{PRB}}^{\mathrm{Normal}}\×N_{\mathrm{PRB},\mathrm{all}\_\mathrm{normal}}}=\frac{{\mathrm{TBS}}^{\′}}{{\mathrm{TBS}}_{\mathrm{init}}}\·\frac{{\mathrm{TBS}}_{\mathrm{init}}}{N_{\mathrm{RE},\mathrm{PRB}}^{\mathrm{Normal}}\×N_{\mathrm{PRB},\mathrm{all}\_\mathrm{normal}}}=(1-{\mathrm{\λ}}_2+{\mathrm{\λ}}_1\·{\mathrm{\λ}}_2)\·{\mathrm{\η}}_{\mathrm{CQI}\_\mathrm{init}}---\left(3\right)$

Step 53:eNodeB is by η _UsedSearch the MCS grade (I that the MCS form obtains this moment _{MCS, Used}) and corresponding TBS grade I _{TBS, Used}

Step 54:eNodeB is according to PRB number (N _{PRB, all_normal}) and TBS grade (I _{TBS, Used}) search the data volume TBS ' that the TBS form is determined the PDSCH actual transmissions;

Step 55:eNodeB passes through the DCI signaling by N _{PRB, all_normal}And I _{MCS, Used}Send to UE;

Step 56:UE basis is by the N that indicates in the DCI signaling _{PRB, all_normal}And I _{MCS, Used}Determine the data volume TBS ' that receives.

Finish (End).

Referring to Fig. 6, the embodiment of the present invention also provides a kind of wireless communication system, and this system comprises:

Base station 60, for the channel quality indicator CQI information according to terminal to report and current downlink data amount waiting for transmission, be terminal distribution Physical Resource Block PRB; Determine a MCS grade, a MCS grade is less than the 2nd MCS grade, and the 2nd MCS grade is the MCS grade of determining according to the SINR on each PRB of terminal distribution; By searching modulation coding mode MCS form and transmission block size TBS form, obtain a MCS grade and reach the corresponding TBS of total number for the PRB of terminal distribution; Be utilized as the downlink data of the PRB of terminal distribution to the described TBS of terminal transmission;

Terminal 61, be used to receiving described downlink data.

Described base station 60 for:

According to described CQI information, determine the highest spectral efficiency (being target spectrum efficiency) that the current wireless channel can be supported;

According to described highest spectral efficiency, determine the spectrum efficiency of the actual use of down physical channel, this spectrum efficiency is less than described highest spectral efficiency;

By searching the MCS form, obtain the MCS grade corresponding to spectrum efficiency of the actual use of described down physical channel, and be a MCS grade by this MCS classification.

Described base station 60 for:

According to following formula, determine the spectrum efficiency of the actual use of down physical channel: η _Used=(1-λ ₂+ λ ₁λ ₂) η _{CQI_init}, wherein, η _{CQI_init}For the highest spectral efficiency (being target spectrum efficiency) that described current wireless channel can be supported, λ ₁The expression base station be in the PRB that distributes of UE punching PRB to the number of the Resource Unit RE that comprises and the conventional PRB ratio to the number of the RE that comprises, λ ₂The expression base station is the ratio of total number that in the PRB that distributes of UE, PRB pair of punching and PRB are right.

Described base station 60 also for:

By being included as total number of PRB of terminal distribution and the signaling of a MCS grade, send to terminal;

Described terminal 61 also for:

According to total number and the MCS grade of the PRB that receives, determining needs the TBS that receives, and according to the TBS downlink data receiving of determining.

Described terminal 61 for:

From downlink signaling, receiving the total number of the current PRB that uses, be N _PRB

By searching MCS form and TBS form, obtain MCS grade and a N _PRBCorresponding TBS, needing to be defined as by this TBS the TBS that receives.

Referring to Fig. 7, the embodiment of the present invention also provides ，Gai base station, a kind of base station to comprise:

Resource allocation unit 70, for the channel quality indicator CQI information according to terminal to report and current downlink data amount waiting for transmission, be terminal distribution Physical Resource Block PRB;

MCS classification unit 71, for determining a MCS grade, a MCS grade is less than the 2nd MCS grade, and the 2nd MCS grade is the MCS grade of determining according to the SINR on each PRB of terminal distribution;

TBS determining unit 72, for by searching modulation coding mode MCS form and transmission block size TBS form, obtain a MCS grade and reach the corresponding TBS of total number for the PRB of terminal distribution;

Data transmission unit 73, be used to the PRB that the is utilized as terminal distribution downlink data to the described TBS of terminal transmission.

Described MCS classification unit 71 comprises:

The spectrum efficiency determining unit, for the highest spectral efficiency (being target spectrum efficiency) of determining that according to described CQI information the current wireless channel can be supported;

The spectrum efficiency adjustment unit, for according to described highest spectral efficiency, determining the spectrum efficiency of the actual use of down physical channel, this spectrum efficiency is less than described highest spectral efficiency;

MCS table lookup unit, for by searching the MCS form, obtain the MCS grade corresponding to spectrum efficiency of the actual use of described down physical channel, and be a MCS grade by this MCS classification.

Described spectrum efficiency adjustment unit is used for:

According to following formula, determine the spectrum efficiency of the actual use of down physical channel: η _Used=(1-λ ₂+ λ ₁λ ₂) η _{CQI_init}, wherein, η _{CQI_init}For the highest spectral efficiency (being target spectrum efficiency) that described current wireless channel can be supported, λ ₁The expression base station be in the PRB that distributes of UE punching PRB to the number of the Resource Unit RE that comprises and the conventional PRB ratio to the number of the RE that comprises, λ ₂The expression base station is the ratio of total number that in the PRB that distributes of UE, PRB pair of punching and PRB are right.

This base station also comprises:

Signalling unit 74, send to terminal for total number of the PRB that will be included as terminal distribution and the signaling of a MCS grade, the TBS that need to receive according to total number and the MCS classification of this PRB with indicating terminal.

Referring to Fig. 8, the embodiment of the present invention also provides a kind of terminal, and this terminal comprises:

Signaling receiving element 80, be used to total number of receiving the Physical Resource Block PRB that is included as this terminal distribution that sends base station and the signaling of MCS grade;

TBS determining unit 81, for the total number according to described PRB and MCS grade, need to determine the TBS that receives;

Data receiver unit 82, receive for the TBS according to determining the downlink data that send base station.

Described TBS determining unit 81 for:

By searching MCS form and TBS form, obtain the corresponding TBS of total number of described MCS grade and described PRB, by this TBS, needing to be defined as the TBS that receives.

To sum up, beneficial effect of the present invention comprises:

In the scheme that the embodiment of the present invention provides, after base station is terminal distribution PRB according to the CQI information of terminal to report and current downlink data amount waiting for transmission, determine the little MCS grade of the 2nd MCS grade that beguine is determined according to the SINR on each PRB of terminal distribution, then by searching transmission block size TBS table, obtain a MCS grade and reach the corresponding TBS of total number for the PRB of terminal distribution, and be utilized as the downlink data of the PRB of terminal distribution to this TBS of terminal transmission.Visible, in the present invention due to a MCS grade of determining less than the 2nd MCS grade, the actual spectrum efficiency that reaches also just reduces during transmitting downlink data so, the also corresponding reduction of code check of adopting, and then improved the reliability of transfer of data, reduce the probability that HARQ retransmits, effectively reduced the waste to interface-free resources.

Obviously, those skilled in the art can carry out various changes and modification and not break away from the spirit and scope of the present invention the present invention.Like this, if within of the present invention these are revised and modification belongs to the scope of the claims in the present invention and equivalent technologies thereof, the present invention also is intended to comprise these changes and modification interior.

Claims (7)

1. a downlink data transmission method, is characterized in that, the method comprises:

Base station, according to channel quality indicator CQI information and the current downlink data amount waiting for transmission of terminal to report, is terminal distribution Physical Resource Block PRB;

The highest spectral efficiency that the current wireless channel can be supported is determined according to described CQI information in base station; The spectrum efficiency η of the actual use of down physical channel is determined in base station according to following formula _Used: η _Used=(1-λ ₂+ λ ₁λ ₂) η _{CQI_init}, wherein, η _{CQI_init}For the highest spectral efficiency that described current wireless channel can be supported, λ ₁The expression base station be in the PRB of terminal distribution punching PRB to the number of the Resource Unit RE that comprises and the conventional PRB ratio to the number of the RE that comprises, λ ₂The expression base station is the ratio of total number that PRB pair of PRB centering punching and the PRB of terminal distribution is right; This spectrum efficiency η _UsedLess than described highest spectral efficiency; Base station, by searching the MCS form, obtains the MCS grade corresponding to spectrum efficiency of the actual use of described down physical channel, and is a MCS grade by this MCS classification; The one MCS grade is less than the 2nd MCS grade, and the 2nd MCS grade is the MCS grade of determining according to the Signal to Interference plus Noise Ratio SINR on each PRB of terminal distribution;

Base station, by searching MCS form and transmission block size TBS form, obtains a MCS grade and reaches the corresponding TBS of total number for the PRB of terminal distribution;

Base station is utilized as the downlink data of the PRB of terminal distribution to the described TBS of terminal transmission.

2. the method for claim 1, is characterized in that, after a MCS grade was determined in base station, the method further comprised:

Base station will send to terminal for total number of the PRB of terminal distribution and the information of a MCS grade;

Terminal is according to total number of the PRB that receives and the information of a MCS grade, and determining needs the TBS that receives, and according to the TBS downlink data receiving of determining.

3. method as claimed in claim 2, is characterized in that, described terminal, according to total number of the PRB that receives and the information of a MCS grade, need to determine the TBS that receives to comprise:

By searching MCS form and TBS form, obtain total number and the corresponding TBS of a MCS grade of described PRB, by this TBS, needing to be defined as the TBS that receives.

4. a wireless communication system, is characterized in that, this system comprises:

Base station, for the channel quality indicator CQI information according to terminal to report and current downlink data amount waiting for transmission, be terminal distribution Physical Resource Block PRB; According to described CQI information, determine the highest spectral efficiency that the current wireless channel can be supported; According to following formula, determine the spectrum efficiency η of the actual use of down physical channel _Used: η _Used=(1-λ ₂+ λ ₁λ ₂) η _{CQI_init}, wherein, η _{CQI_init}For the highest spectral efficiency that described current wireless channel can be supported, λ ₁The expression base station be in the PRB of terminal distribution punching PRB to the number of the Resource Unit RE that comprises and the conventional PRB ratio to the number of the RE that comprises, λ ₂The expression base station is the ratio of total number that PRB pair of PRB centering punching and the PRB of terminal distribution is right; This spectrum efficiency η _UsedLess than described highest spectral efficiency; By searching the MCS form, obtain the MCS grade corresponding to spectrum efficiency of the actual use of described down physical channel, and be a MCS grade by this MCS classification; The one MCS grade is less than the 2nd MCS grade, and the 2nd MCS grade is the MCS grade of determining according to the Signal to Interference plus Noise Ratio SINR on each PRB of terminal distribution; By searching MCS form and transmission block size TBS form, obtain a MCS grade and reach the corresponding TBS of total number for the PRB of terminal distribution; Be utilized as the downlink data of the PRB of terminal distribution to the described TBS of terminal transmission; And will be included as total number of PRB of terminal distribution and the signaling of a MCS grade sends to terminal;

Terminal, for the total number according to described PRB and a MCS grade, determining needs the TBS that receives, and according to the TBS downlink data receiving of determining.

5. system as claimed in claim 4, is characterized in that, described terminal is used for:

By searching MCS form and TBS form, obtain the corresponding TBS of total number of a MCS grade and described PRB, by this TBS, needing to be defined as the TBS that receives.

6. a base station, is characterized in that, this base station comprises:

Resource allocation unit, MCS classification unit, TBS determining unit and data transmission unit;

Described resource allocation unit, for the channel quality indicator CQI information according to terminal to report and current downlink data amount waiting for transmission, be terminal distribution Physical Resource Block PRB;

Described MCS classification unit comprises: spectrum efficiency determining unit, spectrum efficiency adjustment unit and MCS table lookup unit;

Described spectrum efficiency determining unit, for determining according to described CQI information the highest spectral efficiency that the current wireless channel can be supported;

Described spectrum efficiency adjustment unit, for determining the spectrum efficiency η of the actual use of down physical channel according to following formula _Used: η _Used=(1-λ ₂+ λ ₁λ ₂) η _{CQI_init}, wherein, η _{CQI_init}For the highest spectral efficiency that described current wireless channel can be supported, λ ₁The expression base station be in the PRB of terminal distribution punching PRB to the number of the Resource Unit RE that comprises and the conventional PRB ratio to the number of the RE that comprises, λ ₂The expression base station is the ratio of total number that in the PRB of terminal distribution, PRB pair of punching and PRB are right; This spectrum efficiency η _UsedLess than described highest spectral efficiency;

Described MCS table lookup unit, for by searching the MCS form, obtain the MCS grade corresponding to spectrum efficiency of the actual use of described down physical channel, and be a MCS grade by this MCS classification; The one MCS grade is less than the 2nd MCS grade, and the 2nd MCS grade is the MCS grade of determining according to the Signal to Interference plus Noise Ratio SINR on each PRB of terminal distribution;

Described TBS determining unit, for by searching MCS form and transmission block size TBS form, obtain a MCS grade and reach the corresponding TBS of total number for the PRB of terminal distribution;

Described data transmission unit, be used to the PRB that the is utilized as terminal distribution downlink data to the described TBS of terminal transmission.

7. base station as claimed in claim 6, is characterized in that, this base station comprises:

The signalling unit, send to terminal for total number of the PRB that will be included as terminal distribution and the signaling of a MCS grade, the TBS that need to receive according to total number and the MCS classification of this PRB with indicating terminal.

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