CN104301073A - Reference signal setting method in mobile communication system - Google Patents

Abstract

A reference signal setting method in a mobile communication system is provided. The present invention presents a solution for space division multiplexing demodulation reference signals in a massive MIMO network. In one embodiment, a RE for demodulating reference signals of an LTE system is divided into two parts, one for transmitting demodulation reference signals which are not space-division-multiplexed, and the other one for transmitting demodulation reference signals in a space division multiplexing manner. The technical solution provided in the present invention solves the problem that the cost for demodulating reference signals in the massive MIMO is too high, and meanwhile maintains the compatibility with existing systems as best as possible.

Description

Reference signal method to set up in a kind of mobile communication system

Technical field

The present invention relates to the scheme of reference signal design in mobile communication technology field, particularly relate to the scheme of the downlink demodulation reference signal (DMRS-Demodulation Reference Signal) in the mobile communication system that have employed extensive Multiinputoutput (Massive MIMO-Massive Multiple Input Multiple Output) technology.

Background technology

In traditional third generation partner program (3GPP – 3rd Generation Partner Project) Long Term Evolution (LTE-Long Term Evolution) system, define three kinds of downlink reference signals:

● the specific reference signal in community (CRS-Cell specific Reference Signal)

●DMRS

● channel status instruction reference signal (CSI-RS:CSI Reference Signal)

Above-mentioned CRS and DMRS is used for data demodulates, and CSI-RS is used for channel information monitoring.Accompanying drawing 1 is that one of them lattice is the least resource unit-resource particle (RE-Resource Element) of LTE based on the CSI-RS pattern of normal cyclic prefix (Normal CP-Normal Cyclic Prefix)-indicated CRS and demodulated reference signal (DMRS-Demodulation Reference Signal) simultaneously in an existing LTE community.LTE system adopts the concept definition RS resource of port: a RS port may be mapped to a physical antenna, is also likely that many physical antennas are by merging the virtual antenna of superposition formation one.In accompanying drawing 1, the numeral of mark is antenna end slogan, and namely antenna port 0 ~ 3 is CRS, and port 7 ~ 10 is DMRS, and port one 5 ~ 22 is CSI-RS.Wherein DMRS and CSI-RS have employed the orthogonal covering codes (OCC-Orthogonal Covering Code) that length is 2, such as port 7,8.

As a kind of new Cellular Networks antenna frame, Massive MIMO becomes a study hotspot recently.The typical feature of Massive mimo system is that quantity by increasing antenna array unit obtains a series of gain to larger value, and such as, power system capacity continues to increase along with the increase of antenna amount in theory; The coherent superposition of transmitting antenna signal reduces transmitting power etc.The typical apply scene of Massive MIMO is the multi-user's quantity raising spectrum efficiency by increasing space division multiplexing.The challenge that Massive MIMO faces is that the expense of descending DMRS may be excessive.For Long Term Evolution (LTE-Long Term Evolution) system, maximum support 4 subscriber equipmenies (UE-User Equipment) carry out multi-user transmission, be assigned with 24 resource particle (RE-Resource Element) as DMRS, account for 14.3% of all available RE.Assuming that Massive MIMO uses identical DMRS expense to support 20 UE multi-user transmissions simultaneously, then DMRS accounts for 71.4% of all available resources, then considers the expense of control signal, and the RE of remaining little ratio is used for transfer of data, greatly reduces efficiency of transmission.The present invention is directed to this problem and disclose a kind of reference signal method to set up.

Summary of the invention

The invention discloses a kind of method in system equipment, wherein, comprise the steps:

A. K group reference signal is mapped to K group physical resource on, wherein be mapped to

B. K group reference signal is mapped in the mode of space division multiplexing to physical resource R ₂on, wherein be mapped to R ₂

C. with the mode mapping group data D of space division multiplexing ₁..., D _kto physical resource R ₃on, wherein D _kbe mapped to R ₃

D. on downlink resource block, send data, described downlink resource block at least comprises physical resource r ₂, R ₃

Wherein, have passed through identical precoding processing, the signal before precoding is respectively k be greater than 1 integer, k is the integer getting K from 1.

Described reference signal with described reference signal constitute data D described in demodulation _krequired DMRS.Above-mentioned 4 steps do not have strict precedence relationship in time, and as an embodiment, the execution sequence of above-mentioned steps is B, A, C, D, and as another embodiment, above-mentioned steps executed in parallel, namely maps (steps A, B, C) while send (step D).Described 1 × N ₁vector, described in 1 × N ₂vector, described in dimension is M × N respectively ₁, M × N ₂, the wherein corresponding transmitting antenna of each row vector, described precoding is the delivery plan that multiaerial system is commonly used, namely wherein M is number of transmit antennas, N ₁, N ₂be respectively length (RE number), it is precoding vector.

Concrete, obtain an aspect according to the present invention, it is characterized in that, described downlink resource block is that 1 Physical Resource Block (PRB) of Long Term Evolution (LTE-A) system definition is right.

For LTE, LTE-A downlink transfer, minimum scheduling particle is PRB couple, the time/frequency source block of to be namely 1 millisecond of (ms-millisecond) frequency domain bandwidth be the duration 180 KHz (kHz-killo Hertz).PRB different on frequency domain is to upper, and the scheduling of multi-user may be different, and therefore for LTE, lte-a system, described downlink resource block is a PRB couple.

Concrete, obtain an aspect according to the present invention, it is characterized in that, described in a resource particle (RE) is taken each Physical Resource Block (PRB) centering.

Described described upper transmission, does not have and other reference signal space division multiplexings, provides not by the channel-estimation information of multi-user interference.But in order to reduce resource overhead, described in the resource taken in 1 PRB is 1 RE.If described in have employed OCC, i.e. code division multiplexing, described in the resource taken is the quantity taking RE in a PRB takies OCC quantity multiplexing on RE divided by described.

Concrete, obtain an aspect according to the present invention, it is characterized in that, at a PRB to inside, described in with described R ₂all the part RE in the RE transmitted for demodulated reference signal (DMRS) in Long Term Evolution (LTE-A) system.

In lte-a system, DMRS takies at most 24 RE at a PRB to inside.Also for ease of the compatibility of maintenance and existing system, described in with described R ₂at a PRB, inside is all distributed on described 24 RE.

Concrete, obtain an aspect according to the present invention, it is characterized in that, at a PRB to inside, described in with described R ₂the RE taken adds up all RE in the RE that equals to transmit for demodulated reference signal (DMRS) in Long Term Evolution (LTE-A) system.

In lte-a system, the RE that DMRS takies has been divided into two parts, and a part is used for another part is used for R ₂.

Concrete, obtain an aspect according to the present invention, it is characterized in that, at a PRB to inside, described in the more described R of the RE taken ₂the RE taken is in the position at frequency domain edge more.

Described on there is no multi-user interference, should be placed in closer to the position of PRB to center, more can embody the right average channel information of PRB.Accordingly, compare in channel estimation occupy higher weight.

Concrete, obtain an aspect according to the present invention, it is characterized in that, described in compared to described have employed power ascension (Power Boosting).

In order to reduce resource overhead, described in only take less resource, and in order to ensure the accuracy of channel estimating, described in adopt power ascension, namely transmission power ratio described in exceed P decibel (dB), described P is by system configuration or predefine.

The invention discloses the method in a kind of subscriber equipment (UE), wherein, comprise the steps:

A. on downlink resource block, receive data, described downlink resource block at least comprises physical resource r ₂, R ₃

B. according to local reference signal respectively to physical resource on signal perform channel estimating operation obtain the first channel information

C. according to local reference signal to physical resource R ₂on signal perform channel estimating operation and obtain second channel information

D. from physical resource R ₃on demodulate data D _{k_1}, D _{k_2}..., D _{k_T}

Wherein, described physical resource on there is no other signals of space division multiplexing, described physical resource R ₂other K-T group reference signals of upper space division multiplexing.K be greater than 1 integer; T is the order number distributed, and is be more than or equal to the integer that 1 is less than or equal to K; K_1, k_2 ..., k_T is the reference signal index distributed, and is all be more than or equal to the integer that 1 is less than or equal to K.

Above-mentioned steps B, the channel estimation method that channel estimating operation in C adopts realizes relevant issues, typical channel estimation method comprises least square (LS-Least Square) channel estimating, least mean-square error (MMSE-Minimum Mean Square Error) channel estimating etc.

Concrete, obtain an aspect according to the present invention, it is characterized in that, described first channel information be used for following one of at least:

The acquisition of-described second channel information

-described data D _{k_1}, D _{k_2}..., D _{k_T}demodulation

As an embodiment:

First channel information adopts LS channel estimation method to obtain, wherein it is physical resource on Received signal strength ./represent vector point except operation.Described k_t travels through k_1, k_2 ..., k_T.

Second channel information adopts MMSE channel estimation method to obtain, and not only considers background noise, also will consider multi-user interference.The channel information comprising multi-user interference is obtained by LS algorithm: ${\mathrm{\η}}_{k\_t}^2=y_{k\_t}^2\·/x_{k\_t}^2.$ Multi-user interference is ${\mathrm{\δ}}^2=E({\mathrm{\η}}_{k\_t}^2\·{\left({\mathrm{\η}}_{k\_t}^2\right)}^H-h_{k\_t}^1\·{\left(h_{k\_t}^1\right)}^H),$ Wherein E (Q) expression is averaged the element in vectorial Q, (Q) ^hrepresent and conjugate transpose is got to vectorial Q.Further, second channel information is obtained by MMSE: $h_{k\_t}^2=F_{k\_t}^2\·{\left(\begin{array}{c}\left[\begin{array}{cc}{u}^2/({\mathrm{\δ}}^2+u^2)\·{\mathrm{\η}}_{k\_t}^2& h_{k\_t}^1\end{array}\right]\end{array}\right)}^{\′}.$ Wherein physical resource R ²on Received signal strength, be 1 × N ₂vector, the transposition of (Q) ' mark Q, channel estimation filters by statistics time-frequency correlation properties between each RE taken determine, are N ₂× N ₂matrix, described k_t travels through k_1, k_2 ..., k_T.

As another embodiment:

Described data D _{k_1}, D _{k_2}..., D _{k_T}demodulation by MMSE balanced realization, d=h ^hz/ (| h| ²+ δ ²+ N ₀), wherein h is the second channel information estimated, δ ²multi-user interference, N ₀be background noise, z is described physical resource R ₃a RE on the data that receive.

The invention discloses a kind of system side equipment, it is characterized in that, this equipment comprises:

First module: map K group reference signal to K group physical resource on, wherein be mapped to

Second module: map K group reference signal in the mode of space division multiplexing to physical resource R ₂on, wherein be mapped to R ₂

3rd module: with the mode mapping group data D of space division multiplexing ₁..., D _kto physical resource R ₃on, wherein D _kbe mapped to R ₃

Four module: send data on downlink resource block, described downlink resource block at least comprises physical resource r ₂, R ₃

Wherein, have passed through identical precoding processing, the signal before precoding is respectively k be greater than 1 integer, k is the integer getting K from 1.

The invention discloses a kind of subscriber equipment (UE), it is characterized in that, this equipment comprises:

First module: receive data on downlink resource block, described downlink resource block at least comprises physical resource r ₂, R ₃

Second module: according to local reference signal respectively to physical resource on signal perform channel estimating operation obtain the first channel information

3rd module: according to local reference signal to physical resource R ₂on signal perform channel estimating operation and obtain second channel information

Four module: from physical resource R ₃on demodulate data D _{k_1}, D _{k_2}..., D _{k_T}

Wherein, described physical resource on there is no other signals of space division multiplexing, described physical resource R ₂other K-T group reference signals of upper space division multiplexing.K be greater than 1 integer; T is the order number distributed, and is be more than or equal to the integer that 1 is less than or equal to K; K_1, k_2 ..., k_T is the reference signal index distributed, and is all be more than or equal to the integer that 1 is less than or equal to K.

The invention solves the problem that in Massive mimo system, DMRS expense is too high, save resource overhead by space division multiplexing on the part resource of a DMRS port and ensure that higher channel estimating performance simultaneously.In addition, the present invention at utmost maintains the compatibility with existing system.

Accompanying drawing explanation

By reading the detailed description done non-limiting example done with reference to the following drawings, other features, objects and advantages of the present invention will become more apparent:

Fig. 1 shows an example of the descending RS pattern of existing LTE community;

Fig. 2 shows downlink reference signal according to an embodiment of the invention and is mapped to the schematic diagram of LTE system on the RE of DMRS;

Fig. 3 shows part downlink reference signal according to an embodiment of the invention and is mapped to schematic diagram on the RE of the non-DMRS of LTE system;

Fig. 4 shows the structured flowchart for the processing unit in base station according to an embodiment of the invention;

Fig. 5 shows the structured flowchart for the processing unit in UE according to an embodiment of the invention;

Embodiment

Hereafter will be described in further detail technical scheme of the present invention by reference to the accompanying drawings, and it should be noted that, when not conflicting, the feature in the embodiment of the application and embodiment can combine arbitrarily mutually.

Embodiment 1

Embodiment 1 is that downlink reference signal is mapped to the schematic diagram of LTE system on the RE of DMRS, as shown in Figure 2.

Base station equipment maps 16 groups of reference signals to 16 groups of physical resources on, wherein be mapped to 1≤k≤16, take a RE, 16 RE are as shown in first area in accompanying drawing 2 altogether.Base station equipment maps 16 groups of reference signals in the mode of space division multiplexing to physical resource R ₂on, wherein be mapped to R ₂, 1≤k≤16.Described R ₂as shown in the second area in accompanying drawing 2.Base station equipment is with the mode mapping group data D of space division multiplexing ₁..., D ₁₆to physical resource R ₃on, wherein D _kbe mapped to R ₃, 1≤k≤16.Described R ₃as shown in the blank RE in accompanying drawing 2.Base station equipment descending PRB on send, d ₁..., D ₁₆.Wherein, d _khave passed through identical precoding processing.

In accompanying drawing 2, first area and second area just in time cover 24 RE for DMRS of traditional LTE system.Further, the RE of the relative second area of RE of first area is in the position at relatively frequency domain center, RE based on first area carries out the channel information that the obtains mean value closer to the right channel information of whole PRB, is therefore more suitable for occupying larger weight when channel equalization.

Embodiment 2

Embodiment 2 is schematic diagrames that part downlink reference signal is mapped on the RE of the non-DMRS of LTE system, as shown in Figure 3.The difference of embodiment 2 and embodiment 1 is the setting of first area.In embodiment 2,16 RE of first area contain the RE of 8 RE for DMRS and 8 non-DMRS, and second area is identical with embodiment 1.Compare with embodiment 1, the first area in embodiment 2, therefore can closer to the mean value of the right channel information of whole PRB more near the position at frequency domain center.

Embodiment 3

Embodiment 3 is the structured flowcharts for the processing unit in base station (eNB), as shown in Figure 4.In accompanying drawing 4, eNB device 300 is by mapping device 301, and mapping device 302, mapping device 303, dispensing device 304 is formed.Wherein mapping device 301 maps K group reference signal to K group physical resource on, wherein be mapped to ; Mapping device 302 maps K group reference signal in the mode of space division multiplexing to physical resource R ₂on, wherein be mapped to R ₂; Mapping device 303 is with the mode mapping group data D of space division multiplexing ₁..., D _kto physical resource R ₃on, wherein D _kbe mapped to R ₃; Dispensing device 304 sends data on downlink resource block, and described downlink resource block at least comprises physical resource r ₂, R ₃.Wherein, have passed through identical precoding processing, the signal before precoding is respectively k be greater than 1 integer, k is the integer getting K from 1.

Embodiment 4

Embodiment 4 is the structured flowcharts for the processing unit in UE, as shown in Figure 5.In accompanying drawing 5, UE device 400 is by receiving system 401, and processing unit 402, processing unit 403, processing unit 404 is formed.Wherein receiving system 401 receives data on downlink resource block, and described downlink resource block at least comprises physical resource r ₂, R ₃; Processing unit 402 is according to local reference signal respectively to physical resource on signal perform channel estimating operation obtain the first channel information; Processing unit 403 is according to local reference signal and first channel information, to physical resource R ₂on signal perform channel estimating operation and obtain second channel information; Processing unit 403 according to the first channel information and second channel information from physical resource R ₃on demodulate data D _{k_1}, D _{k_2}..., D _{k_T}.Wherein, described physical resource on there is no other signals of space division multiplexing, described physical resource R ₂other K-T group reference signals of upper space division multiplexing.K be greater than 1 integer; T is the order number distributed, and is be more than or equal to the integer that 1 is less than or equal to K; K_1, k_2 ..., k_T is the reference signal index distributed, and is all be more than or equal to the integer that 1 is less than or equal to K.

The all or part of step that one of ordinary skill in the art will appreciate that in said method can be carried out instruction related hardware by program and complete, and described program can be stored in computer-readable recording medium, as read-only memory, and hard disk or CD etc.Optionally, all or part of step of above-described embodiment also can use one or more integrated circuit to realize.Accordingly, each modular unit in above-described embodiment, can adopt example, in hardware to realize, and also can be realized by the form of software function module, the application is not limited to the combination of the software and hardware of any particular form.

The above, be only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention.Within the spirit and principles in the present invention all, any amendment made, equivalent replacement, improves, all should be included within protection scope of the present invention.

Claims (11)

1. the method in system equipment, wherein, comprises the steps:

A. K group reference signal is mapped to K group physical resource on, wherein be mapped to

B. K group reference signal is mapped in the mode of space division multiplexing to physical resource R ₂on, wherein be mapped to R ₂

C. with the mode mapping group data D of space division multiplexing ₁..., D _kto physical resource R ₃on, wherein D _kbe mapped to R ₃

D. on downlink resource block, send data, described downlink resource block at least comprises physical resource r ₂, R ₃

Wherein, have passed through identical precoding processing, the signal before precoding is respectively k be greater than 1 integer, k is the integer getting K from 1.

2. method according to claim 1, is characterized in that, described downlink resource block is that 1 Physical Resource Block (PRB) of Long Term Evolution (LTE-A) system definition is right.

3. method according to claim 1, is characterized in that, described in a resource particle (RE) is on average taken each Physical Resource Block (PRB) centering.

4. method according to claim 1, is characterized in that, at a PRB to inside, described in with described R ₂all the part RE in the RE transmitted for demodulated reference signal (DMRS) in Long Term Evolution (LTE-A) system.

5. method according to claim 1, is characterized in that, at a PRB to inside, described in with described R ₂the RE taken adds up all RE in the RE that equals to transmit for demodulated reference signal (DMRS) in Long Term Evolution (LTE-A) system.

6. method according to claim 1, is characterized in that, at a PRB to inside, described in the more described R of the RE taken ₂the RE taken is in the position at frequency domain edge more.

7. method according to claim 1, is characterized in that, described in described in comparing have employed power ascension (Power Boosting).

8. the method in subscriber equipment (UE), wherein, comprises the steps:

A. on downlink resource block, receive data, described downlink resource block at least comprises physical resource r ₂, R ₃

B. according to local reference signal respectively to physical resource on signal perform channel estimating operation obtain the first channel information

C. according to local reference signal to physical resource R ₂on signal perform channel estimating operation and obtain second channel information

D. from physical resource R ₃on demodulate data D _{k_1}, D _{k_2}..., D _{k_T}

Wherein, described physical resource on there is no other signals of space division multiplexing, described physical resource R ₂other K-T group reference signals of upper space division multiplexing.K be greater than 1 integer; T is the order number distributed, and is be more than or equal to the integer that 1 is less than or equal to K; K_1, k_2 ..., k_T is the reference signal index distributed, and is all be more than or equal to the integer that 1 is less than or equal to K.

9. method according to claim 8, is characterized in that, described first channel information be used for following one of at least:

The acquisition of-described second channel information

-described data D _{k_1}, D _{k_2}..., D _{k_T}demodulation.

10. a system side equipment, is characterized in that, this equipment comprises:

First module: map K group reference signal to K group physical resource on, wherein be mapped to

Second module: map K group reference signal in the mode of space division multiplexing to physical resource R ₂on, wherein be mapped to R ₂

3rd module: with the mode mapping group data D of space division multiplexing ₁..., D _kto physical resource R ₃on, wherein D _kbe mapped to R ₃

Four module: send data on downlink resource block, described downlink resource block at least comprises physical resource r ₂, R ₃

Wherein, have passed through identical precoding processing, the signal before precoding is respectively k be greater than 1 integer, k is the integer getting K from 1.

11. 1 kinds of subscriber equipmenies (UE), it is characterized in that, this equipment comprises:

First module: receive data on downlink resource block, described downlink resource block at least comprises physical resource r ₂, R ₃

Second module: according to local reference signal respectively to physical resource on signal perform channel estimating operation obtain the first channel information

3rd module: according to local reference signal to physical resource R ₂on signal perform channel estimating operation and obtain second channel information

Four module: from physical resource R ₃on demodulate data D _{k_1}, D _{k_2}..., D _{k_T}

Wherein, described physical resource on there is no other signals of space division multiplexing, described physical resource R ₂other K-T group reference signals of upper space division multiplexing.K be greater than 1 integer; T is the order number distributed, and is be more than or equal to the integer that 1 is less than or equal to K; K_1, k_2 ..., k_T is the reference signal index distributed, and is all be more than or equal to the integer that 1 is less than or equal to K.